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  • DHCP and DNS services configuration for VOIP system, windows domain, etc

    - by Stemen
    My company has numerous physical offices (for purposes of this discussion, 15 buildings). Some of them are well-connected to our primary data center via fiber. Others will be connected to the data center by P2P T1. We are in the beginning stages of implementing an Avaya VOIP telephone system, and we will be replacing a significant portion of our network infrastructure in the process. In tandem with the phone system implementation, we are going to be re-addressing some of our networks, and consolidating most of our Windows domains into one (not all domains, just most). We currently have quite a few Windows domains, and they of course each have their own DNS zones. A few of those networks currently use DHCP, but the majority use static IP assignments for every device. I'm tired of managing static assignments -- I want to use DHCP configuration on everything except servers. Printers and etc will have DHCP reservations. The new IP phones will need to get IP addresses from DHCP, though they need to be in a separate VLAN from the computers/printers/etc. The computers and printers need to be registered in DNS. That's currently handled by the Windows DHCP servers on each of the respective domains. We need to place a priority on DHCP and DNS being available on a per-site basis (in case something were to interrupt the WAN connection) for computers and (primarily) phones. Smaller locations (which will have IP phones but not be a member of any Windows domain) will not have any Windows DNS/DHCP server(s) available. We also are looking for the easiest way to replace a part if it were to fail. That is to say, if a server/appliance/router hosting DHCP were to crash hard, and we couldn't extremely quickly recover the DHCP reservations and leases (and subsequently restore them onto a cold spare), we anticipate that bad things could happen. What is the best idea for how to re-implement DNS and DHCP keeping all of the above in mind? Some thoughts that have been raised (by myself or my coworkers): Use Windows DNS and DHCP servers, where they exist, and use IP helpers to route DHCP requests to some other Windows server if necessary. May not be acceptable if the WAN goes down and clients don't get a DHCP response. Use Windows DNS (everywhere, over WAN in some cases) and a mix of Windows DHCP and DHCP provided by Cisco routers. Every site would be covered for DHCP, but from what I've read, Cisco routers can't handle dynamic registration of DHCP clients to Windows DNS servers, which might create a problem where Cisco routers are used for DHCP. Use Windows DNS (everywhere, over WAN in some cases) and a mix of Windows DHCP and DHCP provided by some service running on an extremely low-price linux server. Is there any such software that would allow DHCP leases granted by these linux boxes to be dynamically registered on the Windows DNS servers? Come up with a Linux solution for both DNS and DHCP, and deploy low-price linux servers to every site. Requirements would be that the DNS zone be multi-master (like Windows DNS integrated with Active Directory), that DHCP be able to make dynamic DNS registrations in that zone, for every lease (where a hostname is provided and is thus possible), and that multiple servers be either authoritative for the same DHCP scope or at least receiving a real-time copy / replication / sync of the leases table so that if one server dies, we still know which MAC has what address. Purchase dedicated DNS/DHCP appliances, deploying to all sites. From what I read/see, this solves all of our technical problems. Then come the financial problems... I don't have a ton of money to spend on this. Or, some other solution that we've thus far overlooked and will consider upon recommendation. Can Cisco routers or Windows servers sync DHCP lease tables so that multiple servers can be authoritative (or active/passive for all I care) for the same scope, in case one of the partners were to fail? I've read online (repeatedly) that ISC's DHCP is able to maintain the same lease table across multiple servers, in order to solve this problem. Does anyone have any experience or advice to regarding that?

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  • Multiple data centers and HTTP traffic: DNS Round Robin is the ONLY way to assure instant fail-over?

    - by vmiazzo
    Hi, Multiple A records pointing to the same domain seem to be used almost exclusively to implement DNS Round Robin as a cheap load balancing technique. The usual warning against DNS RR is that it is not good for high availability. When 1 IP goes down clients will continue to use it for minutes. A load balancer is often suggested as a better choice. Both claims are not completely true: When the traffic is HTTP then, most of the HTML browsers are able to automatically try the next A record if the previous is down, without a new DNS look-up. Read here chapter 3.1 and here. When multiple data centers are involved then, DNS RR is the only option to distribute traffic across them. So, is it true that, with multiple data centers and HTTP traffic, the use of DNS RR is the ONLY way to assure instant fail-over when one data center goes down? Thanks, Valentino Edit: Off course each data center has a local Load Balancer with hot spare. It's OK to sacrifice session affinity for an instant fail-over. AFAIK the only way for a DNS to suggest a data center instead of another is to reply with just the IP (or IPs) associated to that data center. If the data center becomes unreachable then all those IP are also unreachables. This means that, even if smart HTML browsers are able to instantly try another A record , all the attempts will fail until the local cache entry expires and a new DNS lookup is done, fetching the new working IPs (I assume DNS automatically suggests to a new data center when one fail). So, "smart DNS" cannot assure instant fail-over. Conversely a DNS round-robin permits it. When one data center fail, the smart HTML browsers (most of them) instantly try the other cached A records jumping to another (working) data center. So, DNS round-robin doesn't assure session affinity or the lowest RTT but seems to be the only way to assure instant fail-over when the clients are "smart" HTML browsers. Edit 2: Some people suggest TCP Anycast as a definitive solution. In this paper (chapter 6) is explained that Anycast fail-over is related to BGP convergence. For this reason Anycast can employ from 15 minutes to 20 seconds to complete. 20 seconds are possible on networks where the topology was optimized for this. Probably just CDN operators can grant such fast fail-overs. Edit 3:* I did some DNS look-ups and traceroutes (maybe some expert can double check) and: The only CDN using TCP Anycast seems to be CacheFly, other operators like CDN networks and BitGravity use CacheFly. Seems that their edges cannot be used as reverse proxies. Therefore, they cannot be used to grant instant failover. Akamai and LimeLight seems to use geo-aware DNS. But! They return multiple A records. From traceroutes seems that the returned IPs are on the same data center. So, I'm puzzled on how they can offer a 100% SLA when one data center goes down.

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  • Outlook 2007 Does Not Accept Login Credentials, OWA Webmail Does. Troubleshooting Advice?

    - by Chris
    I am trying to connect Outlook 2007 to Exchange (Hosted Exchange from Rackspace). Soon, I will need to roll this out for our entire office. With the Exchange account added to Outlook, Outlook starts up and asks for the user's username and password. Unfortunately, it doesn't like the password I use for it. I can confirm this username (email address) and password combo works by using Outlook WebMail, and another user (in another network/office) confirmed the Exchange account does work within his Outlook client. In my network/office, I can confirm that an Outlook 2007 client (under Windows 7) can connect to the Hosted Exchange server from Rackspace. However, I have not been able to get Outlook 2007 (under Windows XP SP3) to connect to the very same Exchange server Outlook 2007 (under Windows 7) can connect to. Outlook continuously prompts me for the username and password and does not accept the correct combination. Now, regarding the Outlook client that cannot connect/login to Exchange: The user has full admin rights on the workstation We do not run a domain controller/LDAP The firewall on the workstation has been disabled Real time file scanning in Microsoft Security Essentials has been disabled There are no virus scanning applications that would interface with Outlook or an email server. The Exchange account is setup to run on a newly created Outlook profile The network firewall does not log any blocked attempts A packet capture at the router reveals communication between the workstation and the Exchange server or proxy (though, this is SSL encrypted, so I don't know what the computers are saying) I have applied a fix (Added DWORD value of 0 for DefConnectOpts under HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\RPC) that was recommended to make RPC function when the workstation does not have a default gateway set. Workstation is configured as DHCP. This fix did nothing, and it may be worth noting the RPC subkey was not present until I added it. RPC service is running on the workstation The program is not running under any compatibility mode. Side note: Outlook 2007 installs with compatibility mode for XP enabled by default in windows 7. Outlook 2007 will not even try to connect to exchange if this compatibility mode is checked. In windows xp, I tried checking compatibility mode for windows 2000, and was unable to connect to exchange as well. Here is the specific configuration I've used in a blank outlook profile: Microsoft Exchange Server: ##MASKED##-MBX-C18.mex07a.mlsrvr.com Username: (Full Email Address: [email protected]) Password: ##MASKED## Outlook Anywhere: Connect to Microsoft Exchange using HTTP Exchange Proxy Settings: Proxy Server: mex07a.emailsrvr.com Check "Connect using SSL only" Under "Only connect to proxy servers...", enter: msstd:mex07a.emailsrvr.com Check "On fast networks, connect using HTTP first, then connect using TCP/IP" Check "On slow networks, connect using HTTP first, then connect using TCP/IP" Proxy authentication settings: Basic Authentication Notes: mex07a.mlsrvr.com and mex07a.emailsrvr.com may look incorrect at first glance, but this is not a typo - these instructions were handed down from rackspace and are confirmed to be working, just not on this workstation. I have tried to use the RpcPing utility but must have been using it wrong. I got as far as "Bad Interface Descriptor". It would seem to me getting Outlook and Exchange to work together would be a breeze, especially since everything is done over port 80 with web services. Unfortunately, the user is stuck with WebMail access only, because Outlook won't accept the Exchange credentials. Do you have any ideas of other things I could try to debug this issue further? Any and all help is greatly appreciated. Thank you! -Chris

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  • IPv6: Should I have private addresses?

    - by AlReece45
    Right now, we have a rack of servers. Every server right now has at least 2 IP addresses, one for the public interface, another for the private. The servers that have SSL websites on them have more IP addresses. We also have virtual servers, that are configured similarly. Private Network The private range is currently just used for backups and monitoring. Its a gigabit port, the interface usage does not usually get very high. There are other technologies we're considering using that would use this port: iSCSI (implementations usually recommends dedicating an interface to it, which would be yet another IP network), VPN to get access to the private range (something I'd rather avoid) dedicated database servers LDAP centralized configuration (like puppet) centralized logging We don't have any private addresses in our DNS records (only public addresses). For our servers to utilize the correct IP address for the right interface (and not hard code the IP address) probably requires setting up a private DNS server (So now we add 2 different dns entries to 2 different systems). Public Network Our public range has a variety of services include web, email, and ftp. There is a hardware firewall between our network and the "public" network. We have (relatively secure) method to instruct the firewall to open and close administrative access (web interfaces, ssh, etc) for our current IP address. With either solution discussed, the host-based firewalls will be configured as well. The public network currently runs at a dedicated 20Mbps link. There are a couple of legacy servers with fast-ethernet ports, but they are scheduled for decommissioning. All of the other production boxes have at least 2 Gigabit Ethernet ports. The more traffic-heavy servers have 4-6 available (none is using more than the 2 Gigabit ports right now). IPv6 I want to get an IPv6 prefix from our ISP. So at least every "server" has at least one IPv6 interface. We'll still need to keep the IPv4 addressees up and available for legacy clients (web servers and email at the very least). We have two IP networks right now. Adding the public IPv6 address would make it three. Just use IPv6? I'm thinking about just dumping the private IPv4 range and using the IPv6 range as the primary means of all communications. If an interface starts reaching its capacity, utilize the newly free interfaces to create a trunk. It has the advantage that if either the public or private traffic needs to exceed 1Gbps. The traffic for each interface is already analyzed on a regular basis to predict future bandwidth use. In the rare instances where bandwidth unexpected peaks: utilize QoS to ensure traffic (like our limited SSH access) is prioritized correctly so the problem can be corrected (if possible, our WAN is the bottleneck right now). It also has the advantage of not needing to make an entry for every private address. We may have private DNS (or just LDAP), but it'll be much more limited in scope with less entries to duplicate. Summary I'm trying to make this network as "simple" as possible. At the same time, I want to make sure its reliable, upgradeable, scalable, and (eventually) redundant. Having one IPv6 network, and a legacy IPv4 network seems to be the best solution to me. Regarding using assigned IPv6 addresses for both networks, sharing the available bandwidth on one (more trunked if needed): Are there any technical disadvantages (limitations, buffers, scalability)? Are there any other security considerations (asides from firewalls mentioned above) to consider? Are there regulations or other security requirements (like PCI-DSS) that this doesn't meet? Is there typical software for setting up a Linux network that doesn't have IPv6 support yet? (logging, ldap, puppet) Some other thing I didn't consider?

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  • Bye Bye Year of the Dragon, Hello BPM

    - by Ajay Khanna
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} As 2012 fades and we usher in a New Year, let’s look back at some of the hottest BPM trends and those we’ll be seeing more of in the coming months. BPM is as much about people as it is about technology. As people adopt new ways of engagement, new channels of communications and new devices to interact , the changes are reflected in BPM practices. As Social and Mobile have become an integral part of our personal and professional lives, we’ll see tighter integration of social and mobile with BPM, and more use cases emerging for smarter process management in 2013. And with products and services becoming less differentiated, organizations will strive to differentiate on Customer Experience. Concepts like Pace Layered Architecture and Dynamic Case Management will provide more flexibility and agility to IT groups and knowledge workers. Take a look at some of these capabilities we showcased (see video) at Oracle OpenWorld 2012. Some of these trends that will continue to gain momentum in 2013: Social networks and social media have provided a new way for businesses to engage with customers. A prospect is likely to reach out to their social network before making any purchase. Companies are increasingly engaging with customers in social networks to influence their purchasing decisions, as well as listening to customers via tools like sentiment analysis to see what customers think about a particular product or process. These insights are valuable as companies look to improve their processes. Inside organizations, workers are using social tools to engage with each other to design new products and processes. Social collaboration tools are being used to resolve issues where an employee needs consultation to reach a decision. Oracle BPM Suite includes social interaction as an integral part of its process design and work management to empower today’s business users. Ubiquitous smart mobile devices are trending as a tool of choice for many workers. Many companies are adopting the policy of “Bring Your Own Device,” and the device of choice is a tablet. Devices like smart phones and tablets not only provide mobility to workers and customers, but they also provide additional important information – the context. By integrating the mobile context (location, photos, and preferences) into your processes, organizations can make much more informed decisions, as well as offer more personalized service to customers. Using Oracle ADF Mobile, you can easily create user interfaces for mobile devices and also capture location data for process execution. Customer experience was at the forefront of trending topics in 2012. Organizations are trying to understand their customers better and offer them more personalized and differentiated services. Customer experience is paramount when companies design sales and support processes. Companies are looking to BPM to consistently and efficiently orchestrate customer facing processes across disparate systems, departments and channels of communication. Oracle BPM Suite provides just the right capabilities for organizations to design and deliver an excellent customer experience. Pace Layered Architecture strategy is gaining traction as a way to maximize agility and minimize disruption in organizations. It provides a framework to manage the evolution of your information system when different pieces of it are changing at different rates and need to be updated independent of one another. Oracle Fusion Middleware and Oracle BPM Suite are designed with this in mind. The database layer, integration layer, application layer, and process layer should not be required to change at the same time. Most of the business changes to policy or process can be done at the process layer without disrupting the whole infrastructure. By understanding the type of change needed at a particular level, organizations can become much more agile and efficient. Adaptive Case Management proposes more flexibility to manage processes or cases that do not follow a structured process flow. In such situations, the knowledge worker managing the case needs to evaluate what step should occur next because the sequence of steps can’t be predetermined. Another characteristic is that it requires much more collaboration than straight-through process. As simple processes become automated, and customers adopt more and more self-service, cases that reach the case workers are much more complex and need more investigation. Oracle BPM suite includes comprehensive adaptive case management capability to manage such unstructured and complex processes. Smart BPM or making your BPM intelligent has been the holy grail for BPM practitioners who imagined that one day BPM would become one with Business Intelligence, Business Activity Monitoring and Complex Event Processing, making it much more responsive and helpful in organizational decision making. In 2013, organizations will begin to deploy these intelligent BPM solutions. Oracle offers an integrated solution that brings together the powerful functionality of BI, BAM, event processing, and Real Time Decisions to help organizations create smart process based solutions. In order to help customers reach their BPM goals faster and remove risks associated with BPM initiatives, Oracle has introduced Oracle Process Accelerators, pre-built best practices applications built on Oracle BPM Suite that are fully production grade and ready to deploy. These are exiting times for BPM practitioners and there is so much to look forward to in 2013. We wish you a very happy and prosperous New Year 2013. Happy BPMing!

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  • A Guided Tour of Complexity

    - by JoshReuben
    I just re-read Complexity – A Guided Tour by Melanie Mitchell , protégé of Douglas Hofstadter ( author of “Gödel, Escher, Bach”) http://www.amazon.com/Complexity-Guided-Tour-Melanie-Mitchell/dp/0199798109/ref=sr_1_1?ie=UTF8&qid=1339744329&sr=8-1 here are some notes and links:   Evolved from Cybernetics, General Systems Theory, Synergetics some interesting transdisciplinary fields to investigate: Chaos Theory - http://en.wikipedia.org/wiki/Chaos_theory – small differences in initial conditions (such as those due to rounding errors in numerical computation) yield widely diverging outcomes for chaotic systems, rendering long-term prediction impossible. System Dynamics / Cybernetics - http://en.wikipedia.org/wiki/System_Dynamics – study of how feedback changes system behavior Network Theory - http://en.wikipedia.org/wiki/Network_theory – leverage Graph Theory to analyze symmetric  / asymmetric relations between discrete objects Algebraic Topology - http://en.wikipedia.org/wiki/Algebraic_topology – leverage abstract algebra to analyze topological spaces There are limits to deterministic systems & to computation. Chaos Theory definitely applies to training an ANN (artificial neural network) – different weights will emerge depending upon the random selection of the training set. In recursive Non-Linear systems http://en.wikipedia.org/wiki/Nonlinear_system – output is not directly inferable from input. E.g. a Logistic map: Xt+1 = R Xt(1-Xt) Different types of bifurcations, attractor states and oscillations may occur – e.g. a Lorenz Attractor http://en.wikipedia.org/wiki/Lorenz_system Feigenbaum Constants http://en.wikipedia.org/wiki/Feigenbaum_constants express ratios in a bifurcation diagram for a non-linear map – the convergent limit of R (the rate of period-doubling bifurcations) is 4.6692016 Maxwell’s Demon - http://en.wikipedia.org/wiki/Maxwell%27s_demon - the Second Law of Thermodynamics has only a statistical certainty – the universe (and thus information) tends towards entropy. While any computation can theoretically be done without expending energy, with finite memory, the act of erasing memory is permanent and increases entropy. Life & thought is a counter-example to the universe’s tendency towards entropy. Leo Szilard and later Claude Shannon came up with the Information Theory of Entropy - http://en.wikipedia.org/wiki/Entropy_(information_theory) whereby Shannon entropy quantifies the expected value of a message’s information in bits in order to determine channel capacity and leverage Coding Theory (compression analysis). Ludwig Boltzmann came up with Statistical Mechanics - http://en.wikipedia.org/wiki/Statistical_mechanics – whereby our Newtonian perception of continuous reality is a probabilistic and statistical aggregate of many discrete quantum microstates. This is relevant for Quantum Information Theory http://en.wikipedia.org/wiki/Quantum_information and the Physics of Information - http://en.wikipedia.org/wiki/Physical_information. Hilbert’s Problems http://en.wikipedia.org/wiki/Hilbert's_problems pondered whether mathematics is complete, consistent, and decidable (the Decision Problem – http://en.wikipedia.org/wiki/Entscheidungsproblem – is there always an algorithm that can determine whether a statement is true).  Godel’s Incompleteness Theorems http://en.wikipedia.org/wiki/G%C3%B6del's_incompleteness_theorems  proved that mathematics cannot be both complete and consistent (e.g. “This statement is not provable”). Turing through the use of Turing Machines (http://en.wikipedia.org/wiki/Turing_machine symbol processors that can prove mathematical statements) and Universal Turing Machines (http://en.wikipedia.org/wiki/Universal_Turing_machine Turing Machines that can emulate other any Turing Machine via accepting programs as well as data as input symbols) that computation is limited by demonstrating the Halting Problem http://en.wikipedia.org/wiki/Halting_problem (is is not possible to know when a program will complete – you cannot build an infinite loop detector). You may be used to thinking of 1 / 2 / 3 dimensional systems, but Fractal http://en.wikipedia.org/wiki/Fractal systems are defined by self-similarity & have non-integer Hausdorff Dimensions !!!  http://en.wikipedia.org/wiki/List_of_fractals_by_Hausdorff_dimension – the fractal dimension quantifies the number of copies of a self similar object at each level of detail – eg Koch Snowflake - http://en.wikipedia.org/wiki/Koch_snowflake Definitions of complexity: size, Shannon entropy, Algorithmic Information Content (http://en.wikipedia.org/wiki/Algorithmic_information_theory - size of shortest program that can generate a description of an object) Logical depth (amount of info processed), thermodynamic depth (resources required). Complexity is statistical and fractal. John Von Neumann’s other machine was the Self-Reproducing Automaton http://en.wikipedia.org/wiki/Self-replicating_machine  . Cellular Automata http://en.wikipedia.org/wiki/Cellular_automaton are alternative form of Universal Turing machine to traditional Von Neumann machines where grid cells are locally synchronized with their neighbors according to a rule. Conway’s Game of Life http://en.wikipedia.org/wiki/Conway's_Game_of_Life demonstrates various emergent constructs such as “Glider Guns” and “Spaceships”. Cellular Automatons are not practical because logical ops require a large number of cells – wasteful & inefficient. There are no compilers or general program languages available for Cellular Automatons (as far as I am aware). Random Boolean Networks http://en.wikipedia.org/wiki/Boolean_network are extensions of cellular automata where nodes are connected at random (not to spatial neighbors) and each node has its own rule –> they demonstrate the emergence of complex  & self organized behavior. Stephen Wolfram’s (creator of Mathematica, so give him the benefit of the doubt) New Kind of Science http://en.wikipedia.org/wiki/A_New_Kind_of_Science proposes the universe may be a discrete Finite State Automata http://en.wikipedia.org/wiki/Finite-state_machine whereby reality emerges from simple rules. I am 2/3 through this book. It is feasible that the universe is quantum discrete at the plank scale and that it computes itself – Digital Physics: http://en.wikipedia.org/wiki/Digital_physics – a simulated reality? Anyway, all behavior is supposedly derived from simple algorithmic rules & falls into 4 patterns: uniform , nested / cyclical, random (Rule 30 http://en.wikipedia.org/wiki/Rule_30) & mixed (Rule 110 - http://en.wikipedia.org/wiki/Rule_110 localized structures – it is this that is interesting). interaction between colliding propagating signal inputs is then information processing. Wolfram proposes the Principle of Computational Equivalence - http://mathworld.wolfram.com/PrincipleofComputationalEquivalence.html - all processes that are not obviously simple can be viewed as computations of equivalent sophistication. Meaning in information may emerge from analogy & conceptual slippages – see the CopyCat program: http://cognitrn.psych.indiana.edu/rgoldsto/courses/concepts/copycat.pdf Scale Free Networks http://en.wikipedia.org/wiki/Scale-free_network have a distribution governed by a Power Law (http://en.wikipedia.org/wiki/Power_law - much more common than Normal Distribution). They are characterized by hubs (resilience to random deletion of nodes), heterogeneity of degree values, self similarity, & small world structure. They grow via preferential attachment http://en.wikipedia.org/wiki/Preferential_attachment – tipping points triggered by positive feedback loops. 2 theories of cascading system failures in complex systems are Self-Organized Criticality http://en.wikipedia.org/wiki/Self-organized_criticality and Highly Optimized Tolerance http://en.wikipedia.org/wiki/Highly_optimized_tolerance. Computational Mechanics http://en.wikipedia.org/wiki/Computational_mechanics – use of computational methods to study phenomena governed by the principles of mechanics. This book is a great intuition pump, but does not cover the more mathematical subject of Computational Complexity Theory – http://en.wikipedia.org/wiki/Computational_complexity_theory I am currently reading this book on this subject: http://www.amazon.com/Computational-Complexity-Christos-H-Papadimitriou/dp/0201530821/ref=pd_sim_b_1   stay tuned for that review!

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  • Is Berkeley DB a NoSQL solution?

    - by Gregory Burd
    Berkeley DB is a library. To use it to store data you must link the library into your application. You can use most programming languages to access the API, the calls across these APIs generally mimic the Berkeley DB C-API which makes perfect sense because Berkeley DB is written in C. The inspiration for Berkeley DB was the DBM library, a part of the earliest versions of UNIX written by AT&T's Ken Thompson in 1979. DBM was a simple key/value hashtable-based storage library. In the early 1990s as BSD UNIX was transitioning from version 4.3 to 4.4 and retrofitting commercial code owned by AT&T with unencumbered code, it was the future founders of Sleepycat Software who wrote libdb (aka Berkeley DB) as the replacement for DBM. The problem it addressed was fast, reliable local key/value storage. At that time databases almost always lived on a single node, even the most sophisticated databases only had simple fail-over two node solutions. If you had a lot of data to store you would choose between the few commercial RDBMS solutions or to write your own custom solution. Berkeley DB took the headache out of the custom approach. These basic market forces inspired other DBM implementations. There was the "New DBM" (ndbm) and the "GNU DBM" (GDBM) and a few others, but the theme was the same. Even today TokyoCabinet calls itself "a modern implementation of DBM" mimicking, and improving on, something first created over thirty years ago. In the mid-1990s, DBM was the name for what you needed if you were looking for fast, reliable local storage. Fast forward to today. What's changed? Systems are connected over fast, very reliable networks. Disks are cheep, fast, and capable of storing huge amounts of data. CPUs continued to follow Moore's Law, processing power that filled a room in 1990 now fits in your pocket. PCs, servers, and other computers proliferated both in business and the personal markets. In addition to the new hardware entire markets, social systems, and new modes of interpersonal communication moved onto the web and started evolving rapidly. These changes cause a massive explosion of data and a need to analyze and understand that data. Taken together this resulted in an entirely different landscape for database storage, new solutions were needed. A number of novel solutions stepped up and eventually a category called NoSQL emerged. The new market forces inspired the CAP theorem and the heated debate of BASE vs. ACID. But in essence this was simply the market looking at what to trade off to meet these new demands. These new database systems shared many qualities in common. There were designed to address massive amounts of data, millions of requests per second, and scale out across multiple systems. The first large-scale and successful solution was Dynamo, Amazon's distributed key/value database. Dynamo essentially took the next logical step and added a twist. Dynamo was to be the database of record, it would be distributed, data would be partitioned across many nodes, and it would tolerate failure by avoiding single points of failure. Amazon did this because they recognized that the majority of the dynamic content they provided to customers visiting their web store front didn't require the services of an RDBMS. The queries were simple, key/value look-ups or simple range queries with only a few queries that required more complex joins. They set about to use relational technology only in places where it was the best solution for the task, places like accounting and order fulfillment, but not in the myriad of other situations. The success of Dynamo, and it's design, inspired the next generation of Non-SQL, distributed database solutions including Cassandra, Riak and Voldemort. The problem their designers set out to solve was, "reliability at massive scale" so the first focal point was distributed database algorithms. Underneath Dynamo there is a local transactional database; either Berkeley DB, Berkeley DB Java Edition, MySQL or an in-memory key/value data structure. Dynamo was an evolution of local key/value storage onto networks. Cassandra, Riak, and Voldemort all faced similar design decisions and one, Voldemort, choose Berkeley DB Java Edition for it's node-local storage. Riak at first was entirely in-memory, but has recently added write-once, append-only log-based on-disk storage similar type of storage as Berkeley DB except that it is based on a hash table which must reside entirely in-memory rather than a btree which can live in-memory or on disk. Berkeley DB evolved too, we added high availability (HA) and a replication manager that makes it easy to setup replica groups. Berkeley DB's replication doesn't partitioned the data, every node keeps an entire copy of the database. For consistency, there is a single node where writes are committed first - a master - then those changes are delivered to the replica nodes as log records. Applications can choose to wait until all nodes are consistent, or fire and forget allowing Berkeley DB to eventually become consistent. Berkeley DB's HA scales-out quite well for read-intensive applications and also effectively eliminates the central point of failure by allowing replica nodes to be elected (using a PAXOS algorithm) to mastership if the master should fail. This implementation covers a wide variety of use cases. MemcacheDB is a server that implements the Memcache network protocol but uses Berkeley DB for storage and HA to replicate the cache state across all the nodes in the cache group. Google Accounts, the user authentication layer for all Google properties, was until recently running Berkeley DB HA. That scaled to a globally distributed system. That said, most NoSQL solutions try to partition (shard) data across nodes in the replication group and some allow writes as well as reads at any node, Berkeley DB HA does not. So, is Berkeley DB a "NoSQL" solution? Not really, but it certainly is a component of many of the existing NoSQL solutions out there. Forgetting all the noise about how NoSQL solutions are complex distributed databases when you boil them down to a single node you still have to store the data to some form of stable local storage. DBMs solved that problem a long time ago. NoSQL has more to do with the layers on top of the DBM; the distributed, sometimes-consistent, partitioned, scale-out storage that manage key/value or document sets and generally have some form of simple HTTP/REST-style network API. Does Berkeley DB do that? Not really. Is Berkeley DB a "NoSQL" solution today? Nope, but it's the most robust solution on which to build such a system. Re-inventing the node-local data storage isn't easy. A lot of people are starting to come to appreciate the sophisticated features found in Berkeley DB, even mimic them in some cases. Could Berkeley DB grow into a NoSQL solution? Absolutely. Our key/value API could be extended over the net using any of a number of existing network protocols such as memcache or HTTP/REST. We could adapt our node-local data partitioning out over replicated nodes. We even have a nice query language and cost-based query optimizer in our BDB XML product that we could reuse were we to build out a document-based NoSQL-style product. XML and JSON are not so different that we couldn't adapt one to work with the other interchangeably. Without too much effort we could add what's missing, we could jump into this No SQL market withing a single product development cycle. Why isn't Berkeley DB already a NoSQL solution? Why aren't we working on it? Why indeed...

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  • Life Technologies: Making Life Easier to Manage

    - by Michael Snow
    12.00 Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-family:"Calibri","sans-serif"; mso-bidi-font-family:"Times New Roman";} When we’re thinking about customer engagement, we’re acutely aware of all the forces at play competing for our customer’s attention. Solutions that make life easier for our customers draw attention to themselves. We tend to engage more when there is a distinct benefit and we can take a deep breath and accept that there is hope in the world and everything isn’t designed to frustrate us and make our lives miserable. (sigh…) When products are designed to automate processes that were consuming hours of our time with no relief in sight, they deserve to be recognized. One of our recent Oracle Fusion Middleware Innovation Award Winners in the WebCenter category, Life Technologies, has recently posted a video promoting their “award winning” solution. The Oracle Innovation Awards are part of the overall Oracle Excellence awards given to customers for innovation with Oracle products. More info here. Their award nomination included this description: Life Technologies delivered the My Life Service Portal as part of a larger Digital Hub strategy. This Portal is the first of its kind in the biotechnology service providing industry. The Portal provides access to Life Technologies cloud based service monitoring system where all customer deployed instruments can be remotely monitored and proactively repaired. The portal provides alerts from these cloud based monitoring services directly to the customer and to Life Technologies Field Engineers. The Portal provides insight into the instruments and services customers purchased for the purpose of analyzing and anticipating future customer needs and creating targeted sales and service programs. This portal not only provides benefits for Life Technologies internal sales and service teams but provides customers a central place to track all pertinent instrument information including: instrument service history instrument status and previous activities instrument performance analytics planned service visits warranty/contract information discussion forums social networks for lab management and collaboration alerts and notifications on all of the above team scheduling for instrument usage promote optional reagents required to keep instruments performing From their website The Life Technologies Instruments & Services Portal Helps You Save Time and Gain Peace of Mind Introducing the new, award-winning, free online tool that enables easier management of your instrument use and care, faster response to requests for service or service quotes, and instant sharing of key instrument and service information with your colleagues. Now – this unto itself is obviously beneficial for their customers who were previously burdened with having to do all of these tasks separately, manually and inconsistently by nature. Now – all in one place and free to their customers – a portal that ties it all together. They now have built the platform to give their customers yet another reason to do business with them – Their headline on their product page says it all: “Life is now easier to manage - All your instrument use and care in one place – the no-cost, no-hassle Instruments and Services Portal.” Of course – it’s very convenient that the company name includes “Life” and now can also promote to their clients and prospects that doing business with them is easy and their sophisticated lab equipment is easy to manage. In an industry full of PhD’s – “Easy” isn’t usually the first word that comes to mind, but Life Technologies has now tied the word to their brand in a very eloquent way. Between our work lives and family or personal lives, getting any mono-focused minutes of dedicated attention has become such a rare occurrence in our current era of multi-tasking that those moments of focus are highly prized. So – when something is done really well – so well that it becomes captivating and urges sharing impulses – I take notice and dig deeper and most of the time I discover other gems not so hidden below the surface. And then I share with those I know would enjoy and understand. In the spirit of full disclosure, I must admit here that the first person I shared the videos below with was my daughter. She’s in her senior year of high school in the midst of her college search. She’s passionate about her academics and has already decided that she wants to study Neuroscience in college and like her mother will be in for the long haul to a PhD eventually. In a summer science program at Smith College 2 summers ago – she sent the family famous text to me – “I just dissected a sheep’s brain – wicked cool!” – This was followed by an equally memorable text this past summer in a research mentorship in Neuroscience at UConn – “Just sliced up some rat brain. Reminded me of a deli slicer at the supermarket… sorry I forgot to call last night…” So… needless to say – I knew I had an audience that would enjoy and understand these videos below and are now being shared among her science classmates and faculty. And evidently - so does Life Technologies! They’ve done a great job on these making them fun and something that will easily be shared among their customers social networks. They’ve created a neuro-archetypal character, “Ph.Diddy” and know that their world of clients in academics, research, and other institutions would understand and enjoy the “edutainment” value in this series of videos on their YouTube channel that pokes fun at the stereotypes while also promoting their products at the same time. They use their Facebook page for additional engagement with their clients and as another venue to promote these videos. Enjoy this one as well! More to be found here: http://www.youtube.com/lifetechnologies Stay tuned to this Oracle WebCenter blog channel. Tomorrow we'll be taking a look at another winner of the Innovation Awards, LADWP - helping to keep the citizens of Los Angeles engaged with their Water and Power provider.

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  • The Sensemaking Spectrum for Business Analytics: Translating from Data to Business Through Analysis

    - by Joe Lamantia
    One of the most compelling outcomes of our strategic research efforts over the past several years is a growing vocabulary that articulates our cumulative understanding of the deep structure of the domains of discovery and business analytics. Modes are one example of the deep structure we’ve found.  After looking at discovery activities across a very wide range of industries, question types, business needs, and problem solving approaches, we've identified distinct and recurring kinds of sensemaking activity, independent of context.  We label these activities Modes: Explore, compare, and comprehend are three of the nine recognizable modes.  Modes describe *how* people go about realizing insights.  (Read more about the programmatic research and formal academic grounding and discussion of the modes here: https://www.researchgate.net/publication/235971352_A_Taxonomy_of_Enterprise_Search_and_Discovery) By analogy to languages, modes are the 'verbs' of discovery activity.  When applied to the practical questions of product strategy and development, the modes of discovery allow one to identify what kinds of analytical activity a product, platform, or solution needs to support across a spread of usage scenarios, and then make concrete and well-informed decisions about every aspect of the solution, from high-level capabilities, to which specific types of information visualizations better enable these scenarios for the types of data users will analyze. The modes are a powerful generative tool for product making, but if you've spent time with young children, or had a really bad hangover (or both at the same time...), you understand the difficult of communicating using only verbs.  So I'm happy to share that we've found traction on another facet of the deep structure of discovery and business analytics.  Continuing the language analogy, we've identified some of the ‘nouns’ in the language of discovery: specifically, the consistently recurring aspects of a business that people are looking for insight into.  We call these discovery Subjects, since they identify *what* people focus on during discovery efforts, rather than *how* they go about discovery as with the Modes. Defining the collection of Subjects people repeatedly focus on allows us to understand and articulate sense making needs and activity in more specific, consistent, and complete fashion.  In combination with the Modes, we can use Subjects to concretely identify and define scenarios that describe people’s analytical needs and goals.  For example, a scenario such as ‘Explore [a Mode] the attrition rates [a Measure, one type of Subject] of our largest customers [Entities, another type of Subject] clearly captures the nature of the activity — exploration of trends vs. deep analysis of underlying factors — and the central focus — attrition rates for customers above a certain set of size criteria — from which follow many of the specifics needed to address this scenario in terms of data, analytical tools, and methods. We can also use Subjects to translate effectively between the different perspectives that shape discovery efforts, reducing ambiguity and increasing impact on both sides the perspective divide.  For example, from the language of business, which often motivates analytical work by asking questions in business terms, to the perspective of analysis.  The question posed to a Data Scientist or analyst may be something like “Why are sales of our new kinds of potato chips to our largest customers fluctuating unexpectedly this year?” or “Where can innovate, by expanding our product portfolio to meet unmet needs?”.  Analysts translate questions and beliefs like these into one or more empirical discovery efforts that more formally and granularly indicate the plan, methods, tools, and desired outcomes of analysis.  From the perspective of analysis this second question might become, “Which customer needs of type ‘A', identified and measured in terms of ‘B’, that are not directly or indirectly addressed by any of our current products, offer 'X' potential for ‘Y' positive return on the investment ‘Z' required to launch a new offering, in time frame ‘W’?  And how do these compare to each other?”.  Translation also happens from the perspective of analysis to the perspective of data; in terms of availability, quality, completeness, format, volume, etc. By implication, we are proposing that most working organizations — small and large, for profit and non-profit, domestic and international, and in the majority of industries — can be described for analytical purposes using this collection of Subjects.  This is a bold claim, but simplified articulation of complexity is one of the primary goals of sensemaking frameworks such as this one.  (And, yes, this is in fact a framework for making sense of sensemaking as a category of activity - but we’re not considering the recursive aspects of this exercise at the moment.) Compellingly, we can place the collection of subjects on a single continuum — we call it the Sensemaking Spectrum — that simply and coherently illustrates some of the most important relationships between the different types of Subjects, and also illuminates several of the fundamental dynamics shaping business analytics as a domain.  As a corollary, the Sensemaking Spectrum also suggests innovation opportunities for products and services related to business analytics. The first illustration below shows Subjects arrayed along the Sensemaking Spectrum; the second illustration presents examples of each kind of Subject.  Subjects appear in colors ranging from blue to reddish-orange, reflecting their place along the Spectrum, which indicates whether a Subject addresses more the viewpoint of systems and data (Data centric and blue), or people (User centric and orange).  This axis is shown explicitly above the Spectrum.  Annotations suggest how Subjects align with the three significant perspectives of Data, Analysis, and Business that shape business analytics activity.  This rendering makes explicit the translation and bridging function of Analysts as a role, and analysis as an activity. Subjects are best understood as fuzzy categories [http://georgelakoff.files.wordpress.com/2011/01/hedges-a-study-in-meaning-criteria-and-the-logic-of-fuzzy-concepts-journal-of-philosophical-logic-2-lakoff-19731.pdf], rather than tightly defined buckets.  For each Subject, we suggest some of the most common examples: Entities may be physical things such as named products, or locations (a building, or a city); they could be Concepts, such as satisfaction; or they could be Relationships between entities, such as the variety of possible connections that define linkage in social networks.  Likewise, Events may indicate a time and place in the dictionary sense; or they may be Transactions involving named entities; or take the form of Signals, such as ‘some Measure had some value at some time’ - what many enterprises understand as alerts.   The central story of the Spectrum is that though consumers of analytical insights (represented here by the Business perspective) need to work in terms of Subjects that are directly meaningful to their perspective — such as Themes, Plans, and Goals — the working realities of data (condition, structure, availability, completeness, cost) and the changing nature of most discovery efforts make direct engagement with source data in this fashion impossible.  Accordingly, business analytics as a domain is structured around the fundamental assumption that sense making depends on analytical transformation of data.  Analytical activity incrementally synthesizes more complex and larger scope Subjects from data in its starting condition, accumulating insight (and value) by moving through a progression of stages in which increasingly meaningful Subjects are iteratively synthesized from the data, and recombined with other Subjects.  The end goal of  ‘laddering’ successive transformations is to enable sense making from the business perspective, rather than the analytical perspective.Synthesis through laddering is typically accomplished by specialized Analysts using dedicated tools and methods. Beginning with some motivating question such as seeking opportunities to increase the efficiency (a Theme) of fulfillment processes to reach some level of profitability by the end of the year (Plan), Analysts will iteratively wrangle and transform source data Records, Values and Attributes into recognizable Entities, such as Products, that can be combined with Measures or other data into the Events (shipment of orders) that indicate the workings of the business.  More complex Subjects (to the right of the Spectrum) are composed of or make reference to less complex Subjects: a business Process such as Fulfillment will include Activities such as confirming, packing, and then shipping orders.  These Activities occur within or are conducted by organizational units such as teams of staff or partner firms (Networks), composed of Entities which are structured via Relationships, such as supplier and buyer.  The fulfillment process will involve other types of Entities, such as the products or services the business provides.  The success of the fulfillment process overall may be judged according to a sophisticated operating efficiency Model, which includes tiered Measures of business activity and health for the transactions and activities included.  All of this may be interpreted through an understanding of the operational domain of the businesses supply chain (a Domain).   We'll discuss the Spectrum in more depth in succeeding posts.

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  • SVM Classification - minimum number of input sets for each class

    - by Amol Joshi
    Im trying to build an app to detect images which are advertisements from the webpages. Once I detect those Ill not be allowing those to be displayed on the client side. From the help that I got here in stackoverflow, I thought SVM is the best approach to my aim. So, I have coded SVM and an SMO myself. The dataset which I have got from UCI data repository has 3280 instances ( Link to Dataset- http://archive.ics.uci.edu/ml/datasets/Internet+Advertisements )where around 400 of them are from class representing Advertisement images and rest of them representing non-advertisement images. Right now Im taking the first 2800 input sets and training the SVM. But after looking at the accuracy rate I realised that most of those 2800 input sets are from non-advertisement image class. So Im getting very good accuracy for that class. So what can I do here? About how many input set shall I give to SVM to train and how many of them for each class? Thanks. Cheers. ( Basically made a new question because the context was different from my previous question. http://stackoverflow.com/questions/1991113/optimization-of-neural-network-input-data )

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  • Nested instances in C#

    - by user32848
    I'm trying to translate some C++ code for a neural net into C#. I first took the C++ code, from a 1993 book, and ran it. Then translated it using the STL and it ran again. Now I'm trying to get it into C# with Visual Web Developer 2008 Express. The original code used "friend" classes and I'm just trying to do the same making everything "public". The following code compiles but only gives null references when run: public class ineuron { public Double weight, activation; public ineuron(Double set_wt) { weight = set_wt; } ... public class netwrk { public oneuron onrn; public ineuron in1, in2, in3, in4; public netwrk( Double inp_1, Double inp_2, Double inp_3, Double inp_4 ) { ineuron in1 = new ineuron(inp_1); ineuron in2 = new ineuron(inp_2); ... and later, in some code called by a button push: netwrk ntw = new netwrk(i_n1, i_n2, i_n3, i_n4); Unfortunately, trying to use: ntw.in1.activation etc. leads to null reference runtime errors. What am I forgetting to do? Barney

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  • How important is PhD research topic to getting a job?

    - by thornate
    EDIT: This has been closed and I realise that I may not have been specific enough with the original title. I ask two questions here: The general one (Does a PhD help get a job?) which has been asked elsewhere, and the specific one (Is it possible to get work outside of the specific research field?). Assume I've already decided going to do the phd. I'm just stressing about the research topic. Well, I'm one year out of university (Mechatronics engineering and Software Eng double bachelors), worked for a few months then got retrenched (yay economy!). It's looking less and less likely that I'll get a job worth having with the job market as it is, so I'm thinking about going back to uni to do a PhD. I figure that by the time I'm done, the job market will have improved and hopefully I'll have something on my resume that is more attractive than spending three years doing customer support for accounting software. So, my question is to people who've done PhD's. Would you say that they were worth the effort? How important is the research topic to future job-seeking success? The idea I have is a computer-sciencey/neural-networks/data-mining thing which I think is very interesting, but not a field I want to be in forever. My potential supervisor claims that employers don't care so much about the topic of the research but rather the peripheral skills that are developed through a PhD; time managment, self-restraint, planning and whatnot. How does this mesh with people's real world experience? I'd appreciate any advice before signing my life on the line for the next three years. See also: Should developers go to grad school? Best reason not to hire a PhD? How to find an entry-level job after you already have a graduate degree?

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  • How do people know so much about programming?

    - by Luciano
    I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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  • Foosball result prediction

    - by Wolf
    In our office, we regularly enjoy some rounds of foosball / table football after work. I have put together a small java program that generates random 2vs2 lineups from the available players and stores the match results in a database afterwards. The current prediction of the outcome uses a simple average of all previous match results from the 4 involved players. This gives a very rough estimation, but I'd like to replace it with something more sophisticated, taking into account things like: players may be good playing as attacker but bad as defender (or vice versa) players do well against a specific opponent / bad against others some teams work well together, others don't skills change over time What would be the best algorithm to predict the game outcome as accurately as possible? Someone suggested using a neural network for this, which sounds quite interesting... but I do not have enough knowledge on the topic to say if that could work, and I also suspect it might take too many games to be reasonably trained. EDIT: Had to take a longer break from this due to some project deadlines. To make the question more specific: Given the following mysql table containing all matches played so far: table match_result match_id int pk match_start datetime duration int (match length in seconds) blue_defense int fk to table player blue_attack int fk to table player red_defense int fk to table player red_attack int fk to table player score_blue int score_red int How would you write a function predictResult(blueDef, blueAtk, redDef, redAtk) {...} to estimate the outcome as closely as possible, executing any sql, doing calculations or using external libraries?

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  • Using game of life or other virtual environment for artificial (intelligence) life simulation? [clos

    - by Berlin Brown
    One of my interests in AI focuses not so much on data but more on biologic computing. This includes neural networks, mapping the brain, cellular-automata, virtual life and environments. Described below is an exciting project that includes develop a virtual environment for bots to evolve in. "Polyworld is a cross-platform (Linux, Mac OS X) program written by Larry Yaeger to evolve Artificial Intelligence through natural selection and evolutionary algorithms." http://en.wikipedia.org/wiki/Polyworld " Polyworld is a promising project for studying virtual life but it still is far from creating an "intelligent autonomous" agent. Here is my question, in theory, what parameters would you use create an AI environment? Possibly a brain environment? Possibly multiple self contained life organisms that have their own "brain" or life structures. I would like a create a spin on the game of life simulation. What if you have a 64x64 game of life grid. But instead of one grid, you might have N number of grids. The N number of grids are your "life force" If all of the game of life entities die in a particular grid then that entire grid dies. A group of "grids" makes up a life form. I don't have an immediate goal. First, I want to simulate an environment and visualize what is going on in the environment with OpenGL and see if there are any interesting properties to the environment. I then want to add "scarce resources" and see if the AI environment can manage resources adequately.

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  • Creating a smart text generator

    - by royrules22
    I'm doing this for fun (or as 4chan says "for teh lolz") and if I learn something on the way all the better. I took an AI course almost 2 years ago now and I really enjoyed it but I managed to forget everything so this is a way to refresh that. Anyway I want to be able to generate text given a set of inputs. Basically this will read forum inputs (or maybe Twitter tweets) and then generate a comment based on the learning. Now the simplest way would be to use a Markov Chain Text Generator but I want something a little bit more complex than that as the MKC basically only learns by word order (which word is more likely to appear after word x given the input text). I'm trying to see if there's something I can do to make it a little bit more smarter. For example I want it to do something like this: Learn from a large selection of posts in a message board but don't weight it too much For each post: Learn from the other comments in that post and weigh these inputs higher Generate comment and post See what other users' reaction to your post was. If good weigh it positively so you make more posts that are similar to the one made, and vice versa if negative. It's the weighing and learning from mistakes part that I'm not sure how to implement. I thought about Artificial Neural Networks (mainly because I remember enjoying that chapter) but as far as I can tell that's mainly used to classify things (i.e. given a finite set of choices [x1...xn] which x is this given input) not really generate anything. I'm not even sure if this is possible or if it is what should I go about learning/figuring out. What algorithm is best suited for this? To those worried that I will use this as a bot to spam or provide bad answers to SO, I promise that I will not use this to provide (bad) advice or to spam for profit. I definitely will not post it's nonsensical thoughts on SO. I plan to use it for my own amusement. Thanks!

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  • Lookup table size reduction

    - by Ryan
    Hello: I have an application in which I have to store a couple of millions of integers, I have to store them in a Look up table, obviously I cannot store such amount of data in memory and in my requirements I am very limited I have to store the data in an embebedded system so I am very limited in the space, so I would like to ask you about recommended methods that I can use for the reduction of the look up table. I cannot use function approximation such as neural networks, the values needs to be in a table. The range of the integers is not known at the moment. When I say integers I mean a 32 bit value. Basically the idea is use some copmpression method to reduce the amount of memory but without losing many precision. This thing needs to run in hardware so the computation overhead cannot be very high. In my algorithm I have to access to one value of the table do some operations with it and after update the value. In the end what I should have is a function which I pass an index to it and then I get a value, and after I have to use another function to write a value in the table. I found one called tile coding http://www.cs.ualberta.ca/~sutton/book/8/node6.html, this one is based on several look up tables, does anyone know any other method?. Thanks.

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  • What's the correct terminology for something that isn't quite classification nor regression?

    - by TC
    Let's say that I have a problem that is basicly classification. That is, given some input and a number of possible output classes, find the correct class for the given input. Neural networks and decision trees are some of the algorithms that may be used to solve such problems. These algorithms typically only emit a single result however: the resulting classification. Now what if I weren't only interested in one classification, but in the posterior probabilities that the input belongs to each of the classes. I.E., instead of the answer "This input belongs in class A", I want the answer "This input belongs to class A with 80%, class B with 15% and class C with 5%". My question is not on how to obtain these posterior probabilities, but rather on the correct terminology to describe the process of finding them. You could call it regression, since we are now trying to estimate a number of real valued numbers, but I am not quite sure if that's right. I feel it's not exactly classification either, it's something in between the two. Is there a word that describes the process of finding the class conditional posterior probabilities that some input belongs in each of the possible output classes? P.S. I'm not exactly sure if this question is enough of a programming question, but since it's about machine learning and machine learning generally involves a decent amount of programming, let's give it a shot.

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  • own drawImage / drawLine in OpenGL

    - by Chrise
    I'm implementing some native 2D-draw functions in my graphics engine for android, but now there's another question coming up, when I observe the performance of my program. At the moment I'm implementing a drawLine/drawImage function. In summary, there are following different values for drawing each different line / image: the color the alpha value the width of the line rotation (only for images) size/scale (also for images) blending method (subrtract, add, normal-alpha) Now, when an imageLine is drawn, I put the CPU-calculated vertex-positions and uv-values for 6 vertices (2 triangles), into a Floatbuffer and draw it immediately with drawArrays, after passing information for drawing (color,alpha, etc.) via uniforms to the shader. When I draw an image, the pre-set VBO is directly drawn after passing information. The first fact I recognized, is: of course drawing Images is much faster, than imagelines (beacuse of VBOs), but also: I cannot pre-put vertex-data into a VBO for imageLines, because imageLines have no static shape like normal images (varying linelength, varying linewidth and the vertex positions of x1,y1 and x2,y2 change too often) That's why I use a normal Floatbuffer, instead of a VBO. So my question is: What's the best way for managing images, and other 2D-graphics functions. For me it's some kind of important, that the user of the engine is able to draw as many images/2D graphics as possible, without loosing to much performance. You can find the functions for drawing images, imagelines, rects, quads, etc. here: https://github.com/Chrise55/LLama3D/blob/master/Llama3DLibrary/src/com/llama3d/object/graphics/image/ImageBase.java Here an example how it looks with many images (testing artificial neural networks), it works fine, but already little bit slow with that many images... :(

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  • how do block websites using Ruckus ZoneDirector

    - by David A. Moody
    In my school we use Ruckus ZoneDirector to control our entire network. I have separate WLANs for faculty, elementary, and secondary. The elementary and secondary networks are set to go offline during recess/lunch breaks, and after school hours. This is working fine. What I need to be able to do is block Youtube access to students while leaving it accessible to teachers (faculty WLAN). Is it possible to do this? Thanks in advance. David.

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  • Cannot enable network discovery on Windows Server 2008 R2

    - by dariom
    I'm trying to enable the Network Discovery feature on a newly installed Windows Server 2008 R2 instance. The network connection is in the Home or Work profile (it is not domain joined). These are the steps I've followed: Within the Network and Sharing Center I select Change advanced sharing settings Then I select the Turn on network discovery option for the current network profile (Home or Work) I then click Save changes If I then go back to the Advanced sharing settings screen the Turn off network discovery option is selected and the machine is not visible to others within the Network node in Windows Explorer. Things I've checked: I can ping the server and connect to it using the machine name/IP address. The Windows Firewall has exceptions for Network Discovery for both Private and Public networks. File and Printer sharing is enabled and I can transfer files to/from the server by connecting to the server using a UNC path. What am I missing here?

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  • Networking with Windows 7

    - by Alix Axel
    I got several computers connected to my home wireless network and I want to make use of some of the features of Windows 7 for home networks but I can't seem to get them working: How do I keep files and folders in sync between specific computers? I'm not talking about Live Sync. How can I stream to Windows Media Player from another computer? I would appreciate if someone could provide me some links / solutions that address my needs. Thanks! To anyone who thinks this question is a duplicate and wants to close it please bare in mind the following: I'm not looking for additional software, I know I can use Live Sync, Dropbox and so on but I'm asking this: how do I configure Windows 7 to sync files between my home network - no Internet required! This has something to do with shared folders and offline files in Windows 7, but I can't get it to work. PS: Please merge with this question: http://superuser.com/questions/139763/networking-with-windows-7

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  • Web Client Service constantly in 'Stopping' state

    - by Mark
    I have a user who's Web Client service constantly reports that it's in the 'Stopping' state and it's hindering her ability to save JMP files to a SharePoint site using the UNC path. She's running Windows XP Service Pack 3. I've tried modifying the Web Client parameters in the registry for UseBasicAuth and FileAttributesLimitInBytes with no luck. When I set the service to Manual and then try to start it after Windows boots up, it starts and then immediately goes into the Stopping state again. Other things I've tried: Removing/Reinstalling her network card Removing/Reinstalling the Client for Microsoft Networks and File and Print Sharing Checked that the BITS and RPC services are running fine (not sure if they're related) Does anyone have any other ideas? Is there a way to repair/rebuild the Web Client service?

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  • win xp wifi networking

    - by user3485532
    I have 2 pcs with win xp and a wifi router ( without outgoing internet connection )...my job was to connect them over wifi to share some files. router was properly configured, both computers connected to wifi without problems, but when I tried to network them I could not see them in workgroup...i changed their names and added them to same workgroup but i couldn't connect pc1 to pc2 ( i could ping router from each pc but pinging other computer resulted in ping timeout) ..now i cant figure out why this is not working since I've done this before on more complex networks and it should work but...( maybe I have gremlins hiding somewhere..) edit1: Firewall is down on both machines( I disengaged it in both control panel and in services) and folder sharing and permissions are ok.. edit2: I know about Ad Hoc network ( wlan-to-wlan, without router/switch ) but that's not what I am trying to accomplish here :)

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  • Daisy Chain a VNC

    - by mastercork889
    Part 1. Theoretically, would daisy chaining a VNC work? EG, If I wanted to VNC into a specific computer on a different network could I VNC into a computer onto that network and ultimately get into the computer I need? So computers A, B, C, D, and E, are all on different networks from one another. I'm at A, could I VNC into B, then C, then D, then E. I understand that I can just VNC into E, but this question is a theoretical question. Part 2. Could I do a sub-looped daisy chain with VNCs? EG, A B C D C B E? Could that theoretically work, or would it screw up somewhere along the trail?

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