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• Fitch Format Proofs - any resources around?

  - by devoured elysium

  I am currently studying Fitch Format first order logic proofs. My lecturer follows closely Language, Proof and Logic by Jon Barwise. I am trying to do some proofs but I am having some trouble getting to understand how to do these proofs. As I have already read what Language Proof and Logic has to offer, I'd like to know if there are any other books or resources around that use the Fitch format for their formal proofs. Plus, having solved exercises would be of great(!) help. Thanks

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• Are proofs worth the effort?

  - by Shashank Jain

  I bought the de-facto book for learning about data structures and algorithms (CLRS). The book is though quite good but the singularity is in the proofs. The book is filled with Lemmas, theorems, peculiar symbols and unimaginable recurrence relations which are very hard to understand. I am able to somehow get the algorithms but the discrete mathematics just not for me. So should I leave them out and just concentrate on algorithims?

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• Formal Languages, Inductive Proofs & Regular Expressions

  - by MarkPearl

  So I am slogging away at my UNISA stuff. I have just finished doing the initial once non stop read through the first 11 chapters of my COS 201 Textbook - “Introduction to Computer Theory 2nd Edition” by Daniel Cohen. It has been an interesting couple of days, with familiar concepts coming up as well as some new territory. In this posting I am going to cover the first couple of chapters of the book. Let start with Formal Languages… What exactly is a formal language? Pretty much a no duh question for me but still a good one to ask – a formal language is a language that is defined in a precise mathematical way. Does that mean that the English language is a formal language? I would say no – and my main motivation for this is that one can have an English sentence that is correct grammatically that is also ambiguous. For example the ambiguous sentence: "I once shot an elephant in my pyjamas.” For this and possibly many other reasons that I am unaware of, English is termed a “Natural Language”. So why the importance of formal languages in computer science? Again a no duh question in my mind… If we want computers to be effective and useful tools then we need them to be able to evaluate a series of commands in some form of language that when interpreted by the device no confusion will exist as to what we were requesting. Imagine the mayhem that would exist if a computer misinterpreted a command to print a document and instead decided to delete it. So what is a Formal Language made up of… For my study purposes a language is made up of a finite alphabet. For a formal language to exist there needs to be a specification on the language that will describe whether a string of characters has membership in the language or not. There are two basic ways to do this: By a “machine” that will recognize strings of the language (e.g. Finite Automata). By a rule that describes how strings of a language can be formed (e.g. Regular Expressions). When we use the phrase “string of characters”, we can also be referring to a “word”. What is an Inductive Proof? So I am not to far into my textbook and of course it starts referring to proofs and different types. I have had to go through several different approaches of proofs in the past, but I can never remember their formal names , so when I saw “inductive proof” I thought to myself – what the heck is that? Google to the rescue… An inductive proof is like a normal proof but it employs a neat trick which allows you to prove a statement about an arbitrary number n by first proving it is true when n is 1 and then assuming it is true for n=k and showing it is true for n=k+1. The idea is that if you want to show that someone can climb to the nth floor of a fire escape, you need only show that you can climb the ladder up to the fire escape (n=1) and then show that you know how to climb the stairs from any level of the fire escape (n=k) to the next level (n=k+1). Does this sound like a form of recursion? No surprise then that in the same chapter they deal with recursive definitions. An example of a recursive definition for the language EVEN would the 3 rules below: 2 is in EVEN If x is in EVEN then so is x+2 The only elements in the set EVEN are those that be produced by the rules above. Nothing to exciting… So if a definition for a language is done recursively, then it makes sense that the language can be proved using induction. Regular Expressions So I am wondering to myself what use is this all – in fact – I find this the biggest challenge to any university material is that it is quite hard to find the immediate practical applications of some theory in real life stuff. How great was my joy when I suddenly saw the word regular expression being introduced. I had been introduced to regular expressions on Stack Overflow where I was trying to recognize if some text measurement put in by a user was in a valid form or not. For instance, the imperial system of measurement where you have feet and inches can be represented in so many different ways. I had eventually turned to regular expressions as an easy way to check if my parser could correctly parse the text or not and convert it to a normalize measurement. So some rules about languages and regular expressions… Any finite language can be represented by at least one if not more regular expressions A regular expressions is almost a rule syntax for expressing how regular languages can be formed regular expressions are cool For a regular expression to be valid for a language it must be able to generate all the words in the language and no other words. This is important. It doesn’t help me if my regular expression parses 100% of my measurement texts but also lets one or two invalid texts to pass as well. Okay, so this posting jumps around a bit – but introduces some very basic fundamentals for the subject which will be built on in later postings… Time to go and do some practical examples now…

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• what practical proofs are there about the Turing completeness of neural nets? what nns can execute c

  - by Albert

  I'm interested in the computational power of neural nets. It is generally accepted that recurrent neural nets are Turing complete. Now I was searching for some papers which proofs this. What I found so far: Turing computability with neural nets, Hava T. Siegelmann and Eduardo D. Sontag, 1991 I think this is only interesting from a theoretical point of view because it needs to have the neuron activity of infinite exactness (to encode the state somehow as a rational number). S. Franklin and M. Garzon, Neural computability This needs an unbounded number of neurons and also doesn't really seem to be that much practical. (Note that another question of mine tries to point out this kind of problem between such theoretical results and the practice.) I'm searching mostly for some neural net which really can execute some code which I can also simulate and test in practice. Of course, in practice, they would have some kind of limited memory. Does anyone know something like this?

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• It is worth planning before jumping in the code?

  - by Rushino

  I always thought that planning is important for a game. But i don't know at which point. Some are telling me to code instead of planning but i feel like its still important because when you will be in the code you will know what to do next more easily. I am currently working on a game that will have lots of content so i decided to start a design document introducing thoses content and at a side-level i am doing proofs of concept to check if it can be done. Parts of each proofs of concept then could be used later in the real game. EDIT: I am working alone on this project. So my question is : It is worth planning before jumping in the code ? Im still interested to know what others have to say about this. Cause i still get some poeple saying i should code instead of thinking.. so what your opinion on this ?

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• Creating Windows Desktop Icon in CMake + CPack + NSIS

  - by Simeon Fitch

  I'm using NSIS package generator in CMake 2.8.1 to distribute a Qt application. Everything is working fine... except the use of CPACK_CREATE_DESKTOP_LINKS to create a desktop link to the application. I've looked through the CMake source (including it's own "bootstrap" installation definition for windows), and as far as I can tell I'm doing the same thing. Here's the relevant section of my CMakeLists.txt file. set(CPACK_GENERATOR NSIS) set(CPACK_NSIS_PACKAGE_NAME "${EWS_APP_NAME}") set(CPACK_NSIS_DISPLAY_NAME "${EWS_APP_NAME}") set(CPACK_NSIS_CONTACT "${EWS_EMAIL}") set(CPACK_PACKAGE_EXECUTABLES "${EXE_TARGET_NAME}" "${EWS_APP_NAME}") set(CPACK_PACKAGE_INSTALL_REGISTRY_KEY "${CMAKE_PROJECT_NAME}-${EWS_VERSION}") # this works set(CPACK_NSIS_MENU_LINKS "${EWS_WEBSITE}" "Homepage for ${EWS_APP_NAME}") # this doesn't set(CPACK_CREATE_DESKTOP_LINKS "${EXE_TARGET_NAME}") # Icon in the add/remove control panel. Must be an .exe file set(CPACK_NSIS_INSTALLED_ICON_NAME bin\\\\${EXE_TARGET_NAME}.exe) set(CPACK_NSIS_URL_INFO_ABOUT "${EWS_WEBSITE}") set(CPACK_NSIS_HELP_LINK "${EWS_WEBSITE}") Any ideas or debugging tips are appreciated!

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• How to allow resizing of QMessageBox in PyQt4

  - by Simeon Fitch

  I'm using the nice feature in QMessageBox to optionally show detailed text to the user. However, the window after expansion is still fairly small, and one immediately tries to resize the window so more of the details are visible. Even after setting what I think are the proper settings it won't allow resizing. Here's the relevant snippet of PyQt4 code: mb = QMessageBox() mb.setText("Results written to '%s'" % filename) mb.setDetailedText(str(myData)) mb.setSizePolicy(QSizePolicy.Expanding, QSizePolicy.Expanding) mb.setSizeGripEnabled(True) Am I missing a step and/or is this at all possible?

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• CodePlex Daily Summary for Friday, February 19, 2010

  CodePlex Daily Summary for Friday, February 19, 2010New ProjectsApplication Management Library: Application Management makes your application life easier. It will automatic do memory management, handle and log unhandled exceptions, profiling y...Audio Service - Play Wave Files From Windows Service: This is a windows service that Check a registry key, when the key is updated with a new wave file path the service plays the wave file.Aviamodels: 3d drawing AviamodelsControl of payment proofs program for Greek citizens: This is a program that is used for Greek citizens who want to keep track of their payment proofs.Cover Creator: Cover Creator gives you the possibility to create and print CD covers. Content of CD is taken from http://www.freedb.org/ or can be added/modyfied ...DevBoard: DevBoard is a webbased scrum tool that helps developers/team get a clear overview of the project progress. It's developed in C# and silverlight.Flex AdventureWorks: The is mostly a skunk-works application to help me get acclimated to CodePlex. The long term goal is to integrate a Flex UI with the AdventureWor...GRE Wordlist: An intuitive and customizable word list for GRE aspirants. Developed in Java using a word list similar to Barron's.Indexer: A desktop file Index and Search tool which allows you to choose a list of folders to index, and then search on later. It is based on Lucene.net an...Project Management Office (PMO) for SharePoint: Sample web part for the Code Mastery event in Boston, February 11, 2010.Restart SQL Audit Policy and Job: Resolve SQL 2008 Audit Network Connectivity Issue.Rounded Corners / DIV Container: The RoundedDiv round corners container is a skin-able, CSS compliant UI control. Select which corners should be rounded, collapse and expand the c...Silverlight Google Search Application: The Silverlight Google Search Application uses Google Search API and behaves like Internet Search Application with option to preview desired page i...Weather Forecast Control: MyWeather forecast control pulls up to date weather forecast information from The Weather Channel for your website.New ReleasesApplication Management Library: ApplicationManagement v1.0: First ReleaseAudio Service - Play Wave Files From Windows Service: Audio Service v1.0: This is a working version of the Audio Service. Please use as you need to.AutoMapper: 1.0.1 for Silverlight 3.0 Alpha: AutoMapper for Silverlight 3.0. Features not supported: IDataReader mapping IListSource mapping All other features are supported.Buzz Dot Net: Buzz Dot Net v.1.10219: Buzz Dot Net Library (Parser & Objects) + WPF Example (using MVVM & Threading)Canvas VSDOC Intellisense: V 1.0.0.0a: This release contains two JavaScript files: canvas-utils.js (can be referenced in both runtime and development environment) canvas-vsdoc.js (must ...Control of payment proofs program for Greek citizens: Payment Proofs: source codeCourier: Beta 2: Added Rx Framework support and re-factored how message registration and un-registration works Blog post explaining the updates and re-factoring c...Cover Creator: Initial release: This is initial stable release. For now only in Polish language.Employee Scheduler: Employee Scheduler 2.2: Small Bug found. Small total hour calculation bug. See http://employeescheduler.codeplex.com/WorkItem/View.aspx?WorkItemId=6059 Extract the files...EnhSim: Release v1.9.7.1: Release v1.9.7.1Implemented Dislodged Foreign Object trinket Whispering Fanged Skull now also procs off Flame shock dots You can toggle bloodlust o...Extend SmallBasic: Teaching Extensions v.007: added SimpleSquareTest added Tortoise.Approve() for virtual proctor how to use virtual proctor: change the path in the proctor.txt file (located i...FolderSize: FolderSize.Win32.1.0.1.0: FolderSize.Win32.1.0.1.0 A simple utility intended to be used to scan harddrives for the folders that take most place and display this to the user...GLB Virtual Player Builder: v0.4.0 Beta: Allows for user to import and use archetypes for building players. The archetypes are contained in the file "archetypes.xml". This file is editab...Google Map WebPart from SharePoint List: GMap Stable Release: GMap Stable ReleaseHenge3D Physics Library for XNA: Henge3D Source (2010-02 R2): Fixed a build error related to an assembly attribute in XBOX 360 builds. Tweaked the controls in the sample when targeting the 360. Reduced the...Indexer: Beta Release 1: Just the initial/rough cut.NukeCS: NukeCS 5.2.3 Source Code: update version to 5.2.3ODOS: ODOS STABLE 1.5.0: Thank you for your patience while we develop this version. Not that much has been added, though. Just doing some sub-conscious stuff to make life...PoshBoard: PoshBoard 3.0 Beta 1: Welcome to the first beta release of PoshBoard 3.0 ! IMPORTANT WARNING : this release is absolutly not feature complete and is error-prone. Okay, ...Restart SQL Audit Policy and Job: Restart SQL 2008 Audit Policy and Job: This folder contains three pieces of source code: Server Audit Status (Started).xml - Import this on-schedule policy into your server's Policy-Ba...SAL- Self Artificial Learning: Artificial Learning 2AQV Working Proof Of Concept: This is the Simulation proof of concept version that comes after the 1aq version. AQ stands for Anwering Questions.SharePoint 2010 Word Automation: SP 2010 Word Automation - Workflow Actions 1.1: This release includes two new custom workflow activities for SharePoint designer Convert Folder Convert Library More information about these new...SharePoint Outlook Connector: Version 1.0.1.1: Exception Logging has been improved.Sharpy: Sharpy 1.2 Alpha: This is the third Sharpy release. A change has been made to allow overriding the master page from the controller. The release contains the single ...Silverlight Google Search Application: SL Google Search App Alpha: This is just a first alpha version of the application, as it looks like when I uploaded it to CodePlex. The application works, requires Silverlight...Starter Kit Mytrip.Mvc.Entity: Mytrip.Mvc.Entity 1.0 RC: EF Membership UserManager FileManager Localization Captcha ClientValidation Theme CrossBrowser VS 2010 RC MVC 2 RC db MSSQL2008thinktecture WSCF.blue: WSCF.blue V1 Update (1.0.6): This release is an update for WSCF.blue V1. Below are the bug fixes made since the V1.0.5 release: The data contract type filter was not including...TS3QueryLib.Net: TS3QueryLib.Net Version 0.18.13.0: Changelog Added overloads to all methods of QueryRunenr class handling permission tasks to allow passing of permission name instead of permissionid...Umbraco CMS: Umbraco 4.1 Beta 2: This is the second beta of Umbraco 4.1. Umbraco 4.1 is more advanced than ever, yet faster, lighter and simpler to use than ever. We, on behalf of...VCC: Latest build, v2.1.30218.0: Automatic drop of latest buildZack's Fiasco - Code Generated DAL: v1.2.4: Enhancements: SQL Server CRUD Stored Procedures added option for USE <db> added option to create or not create INSERT sprocs added option to cr...Most Popular ProjectsRawrWBFS ManagerAJAX Control ToolkitMicrosoft SQL Server Product Samples: DatabaseSilverlight ToolkitWindows Presentation Foundation (WPF)Image Resizer Powertoy Clone for WindowsASP.NETMicrosoft SQL Server Community & SamplesDotNetNuke® Community EditionMost Active ProjectsRawrSharpyDinnerNow.netBlogEngine.NETjQuery Library for SharePoint Web ServicesNB_Store - Free DotNetNuke Ecommerce Catalog Modulepatterns & practices – Enterprise LibraryPHPExcelFacebook Developer ToolkitFluent Ribbon Control Suite

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• Crosstalk 2012

  - by David Dorf

  There are lots of industry conferences, but I consistently hear that Oracle Retail Crosstalk is one of the better ones, presumably because its focused is on helping Oracle Retail's customers interact, share insights, and exchange ideas.  If you're an Oracle Retail customer, I strongly encourage you to register and attend.  Here's why: Two days of fantastic speakers from companies like Daphne, Kohl's, Morrisons, Abercrombie & Fitch, Hot Topic, Talbots, and Disney to name a few. Held in the heart of Chicago with store tours on Michigan Avenue Special Interest discussions on merchandising, supply chain, planning, stores, and technology. Golf, fireworks at Navy Pier, and dancing at Soldier Field And best of all, the conference is free for qualified customers. So I certainly hope to see you there!

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• How To Apply Online For New Passport Or Renewal Of Your Passport [Indian Websites]

  - by Gopinath

  Are you bored wasting time and energy in standing lengthy queues at Passport offices in India to apply a new passport or renew it? Indian Government Passport Office has an online portal that lets you apply for new passport or renew your expiring passport by filling details online. By filling the details online you can complete half of the required formalities sitting at home and the rest of tasks like submitting required proofs, paying money etc at your regional passport office. Saves lot of time. Advantages of Applying For Passport Online Ask anyone who already obtained a passport by visiting the passport office, they will narrate stories of spending long time in queues. In certain office, the length of queues may require you to stand 3 to 4 hours. And sometimes by the time your turn comes, the officers may break for lunch, coffee or the day if your time is very bad. The main advantage of applying for passport using this online portal is – we can skip the process of standing in long queues to obtain tokens for submitting tokens and also we get a pre booked appointment with passport issuing officer for submitting the proofs and paying fees. When you submit the application online, an appointment will be booked automatically for submitting the required documents and fees so that  you can just walk-in to passport office 15 minutes ahead of your appointment. List Of Passport Offices Accepting Online Application Forms I know that you are excited and all set to apply online, but hold on. The online Passport application submission is supported in 37 regional passport offices across India as I write this post. If you are residing in any of these cities, then only you can apply online – Ahemdabad,  Amritsar, Bareilly, Bhopal, Bhubneswar, Chennai, Cochin, Coimbatore, Dehradun, Delhi, Ghaziabad, Guwahati, Hyderabad, Jaipur, Jalandhar, Jammu, Kolkata, Kozhikode, Lucknow, Madurai, Malappuram, Mumbai, Nagpur, Panaji, Patna, Pune, Raipur, Ranchi, Shimla, Srinagar, Surat, Thane, Trichy, Trivandrum, Visakhapatnam. Others should approach the passport office directly. Government is trying to expand this to other locations, so please check if place accepting online registration by visiting registration page(link given below). Types Of Applications Accepted Online The online system accepts following types of passport applications Fresh Passport / Renewal New Passport in lieu of Damaged/Lost Passport Passport for Children up to 15 Years of Age Re-issue of Passport / Additional Booklet Indian Govt. Passport Office Website And Online Application URL To apply for passport online visit the url https://passport.gov.in/pms/Information.jsp using Internet Explorer browser. This site may not work on your Firefox, Chrome or other browsers as the site request users to use Internet Explorer. Here are few other links that will help you get more details on passport application Govt. Of India Passport Office Website Passport Application Fee Structure Information Passport Application Filling Guidelines Passport Application Check List URL For NRIs To Apply Online If you are an NRI then the above links and the list of supported Passport offices are not for you. NRIs should use the URL http://passport.gov.in/nri/OnlineRegistration.jsp for applying passport related services online. For more details you can visit special NRI section on Passport website. CC Image credit: LucasTheExperience This article titled,How To Apply Online For New Passport Or Renewal Of Your Passport [Indian Websites], was originally published at Tech Dreams. Grab our rss feed or fan us on Facebook to get updates from us.

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• ASP.NET MVC solution to a forms application?

  - by Gloria Huang

  Hello, We're building a survey system and utilising ASP.NET MVC and wondered if anyone can offer suggestions on the architecture. Here's the problem we're trying to solve. Essentially an agency sends out several surveys every year. They're very structured and not like SurveyMonkey style of surveys - they're actually applications of feedback. Much like a Visa Application there are lots of things they need to do and sometimes it takes them 2-3 weeks to fill it out. They can upload files (proofs of purchase etc - PDF/JPG) and also multiple "items". Eg. Say for instance they've worked for McDonalds, there could be 20 different franchises, they build a list of locations they've worked. 3 weeks later there could be another 3 new locations and 2 may have closed down. So we need to ensure the forms are able to handle those situations. The forms themselves (markup and data) change every year - I should mention that this for a taxation/finance/budget system. We were thinking of using MVC, using Xml to store the data (temporarily), XSD to validate the data, XSL to transform the data to presentable markup (for them to fill out) and then once they "Submit" an application it gets stored into the DB in relevant areas. When the user starts the application process, they can save the progress so far (we validate whatever they entred and ignore any they havent), save it as an Xml blob and store in the DB. When they're finally ready to submit it, then we do a full validation and upload the files and store them securely (it has their business proofs and accounting statements) and then run some workflows. What I'm really concerned about is how to manage changing forms versions (a year later). How are form/application systems written these days? We have 2 months to pull this off and about 30 forms to deliver. So 30xXML, 30xXSD, 30xXSL.

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• Is there really such a thing as "being good at math"?

  - by thezhaba

  Aside from gifted individuals able to perform complex calculations in their head, I'm wondering if proficiency in mathematics, namely calculus and algebra, has really got to do with one's natural inclination towards sciences, if you can put it that way. A number of students in my calculus course pick up material in seemingly no time whereas I, personally, have to spend time thinking about and understanding most concepts. Even then, if a question that requires a bit more 'imagination' comes up I don't always recognize the concepts behind it, as is the case with calculus proofs, for instance. Nevertheless, I refuse to believe that I'm simply not made for it. I do very well in programming and software engineering courses where a lot of students struggle. At first I could not grasp what they found to be so difficult, but eventually I realized that having previous programming experience is a great asset -- once I've seen and made practical use of the programming concepts learning about them in depth in an academic setting became much easier as I have then already seen their use "in the wild". I suppose I'm hoping that something similar happens with mathematics -- perhaps once the practical idea behind a concept (which authors of textbooks sure do a great job of concealing..) is evident, understanding the seemingly dry and symbolic ideas and proofs would be more obvious? I'm really not sure. All I'm sure of is I'd like to get better at calculus, but I don't yet understand why some of us pick it up easily while others have to spend considerable amounts of time on it and still not have complete understanding if an unusual problem is given.

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• Getting the Item Count of a large sharepoint list in fastest way

  - by sooraj

  I am trying to get the count of the items in a sharepoint document library programatically. The scale I am working with is 30-70000 items. We have usercontrol in a smartpart to display the count . Ours is a TEAM site. This is the code to get the total count SPList VoulnterrList = web.Lists[ListTitle]; SPQuery query = new SPQuery(); query.ViewAttributes = "Scope=\"Recursive\""; string queries = "<Where><Eq><FieldRef Name='ApprovalStatus' /><Value Type='Choice'>Pending</Value></Eq></Where>"; query.Query = queries; SPListItemCollection lstitemcollAssoID = VoulnterrList.GetItems(query); lblCount.Text = "Total Proofs: " + VoulnterrList.Items.Count.ToString() + " Pending Proofs: " + lstitemcollAssoID.Count.ToString(); The problem is this has serious performance issue it takes 75 to 80 sec to load the page. if we comment this page load will decrees to 4 sec. Any better approch for this problem Ours is sharepoint 2007

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• Print a PDF book on line. [closed]

  - by microspino

  I'd like to print my PDF copy of "why's poignant guide to ruby" to read It on paper before to sleep. I have several open source book I'd like to print too and some of them are full color. I know about lulu.com but I never had any experience with It. Can you give me some advice with real world proofs about on-line-print-and ship-to-your house services?

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• Max. power consumption of ATI Radeon X850 Pro graphics adapter

  - by Robert

  What is the maximum power consumption of a graphics adapter with an ATI Radeon X850 Pro GPU? Proofs via sources (downloadable manuals) would be appreciated.

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• Is there a well grounded theory on backward and forward compatibility of formats, languages, grammars and vocabularies?

  - by Breton

  I have a friend who has the specific problem of building a case against the use of a custom HTML <wrapper> tag in some site's markup. Now, intuitively we can answer that use of such a tag is risky, as future HTML specs may define a wrapper tag with semantics that conflict with its use on the site. We can also appeal to a particular section of the HTML5 spec which also recommends against the use of custom tags for this reason. And while I agree with the conclusion, I find these arguments a little on the weak side, on their own. Is there some well grounded and proven theory in computer science from which we can derive this conclusion? Have programming language theorists created proofs about the properties of vocabulary versioning, or some such thing?

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• What's the value of a Facebook fan?

  - by David Dorf

  In his blog posting titled "Why Each Facebook Fan Is Worth $2,000 to J. Crew," Joe Skorupa lays out a simplistic calculation for assigning a value to social media efforts within Facebook. While I don't believe the metric, at least its a metric that can be applied consistently. Trying to explain the ROI to management to start a program, then benchmarking to show progress isn't straightforward at all. Social media isn't really mature enough to have hard-and-fast rules around valuation (yet). When I'm asked by retailers how to measure social media efforts, I usually fess-up and say I can't show an ROI but the investment is so low you might was well take a risk. Intuitively, it just seems like a good way to interact with consumers, and since your competition is doing it, you better do it as well. Vitrue, a social media management company, has calculated a fan as being worth $3.60 per year based on impressions generated in Facebook's news feed. That means a fan base of 1 million translates into at least $3.6 million in equivalent media over a year. Don't believe that number either? Fine, Vitrue now has a tool that let's you adjust the earned media value of a fan. Jump over to http://evaluator.vitrue.com/ and enter your brand's Facebook URL to get an assessment of the current value and potential value. For fun, I compared Abercrombie & Fitch (1,077,480 fans), Gap (567,772 fans), and Wet Seal (294,479 fans). The image below shows the results assuming the default $5 earned media value for a fan. The calculation is more complicated than just counting fans. It also accounts for postings and comments. Its possible for a brand with fewer fans to have a higher value based on frequency and relevancy of posts. The tool gathers data via the Social Graph API for the past 30 days of activity. I'm not sure this tool assigns the correct value either, but hey, its a great start.

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• How does Batcher Merge work at a high level?

  - by Mike

  I'm trying to grasp the concept of a Batcher Sort. However, most resources I've found online focus on proof entirely or on low-level pseudocode. Before I look at proofs, I'd like to understand how Batcher Sort works. Can someone give a high level overview of how Batcher Sort works(particularly the merge) without overly verbose pseudocode(I want to get the idea behind the Batcher Sort, not implement it)? Thanks!

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• Opinion on "loop invariants", and are these frequently used in the industry?

  - by Michael Aaron Safyan

  I was thinking back to my freshman year at college (five years ago) when I took an exam to place-out of intro-level computer science. There was a question about loop invariants, and I was wondering if loop invariants are really necessary in this case or if the question was simply a bad example... the question was to write an iterative definition for a factorial function, and then to prove that the function was correct. The code that I provided for the factorial function was as follows: public static int factorial(int x) { if ( x < 0 ){ throw new IllegalArgumentException("Parameter must be = 0"); }else if ( x == 0 ){ return 1; }else{ int result = 1; for ( int i = 1; i <= x; i++ ){ result*=i; } return result; } } My own proof of correctness was a proof by cases, and in each I asserted that it was correct by definition (x! is undefined for negative values, 0! is 1, and x! is 1*2*3...*x for a positive value of x). The professor wanted me to prove the loop using a loop invariant; however, my argument was that it was correct "by definition", because the definition of "x!" for a positive integer x is "the product of the integers from 1... x", and the for-loop in the else clause is simply a literal translation of this definition. Is a loop invariant really needed as a proof of correctness in this case? How complicated must a loop be before a loop invariant (and proper initialization and termination conditions) become necessary for a proof of correctness? Additionally, I was wondering... how often are such formal proofs used in the industry? I have found that about half of my courses are very theoretical and proof-heavy and about half are very implementation and coding-heavy, without any formal or theoretical material. How much do these overlap in practice? If you do use proofs in the industry, when do you apply them (always, only if it's complicated, rarely, never)?

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• What's a good gift for a theoretical computer science teacher? [closed]

  - by Goose Bumper

  I've been fortunate to have two very good theory professors; I've take 'Algorithms' and 'Advanced Algorithms' with them, and both classes have been outstanding. I'd like to get them "fun" theory books, something like Proofs Without Words but a little cheaper. Any recommendations?

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• Django: select_related and GenericRelation

  - by Parand

  Does select_related work for GenericRelation relations, or is there a reasonable alternative? At the moment Django's doing individual sql calls for each item in my queryset, and I'd like to avoid that using something like select_related. class Claim(models.Model): proof = generic.GenericRelation(Proof) class Proof(models.Model): content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') I'm selecting a bunch of Claims, and I'd like the related Proofs to be pulled in instead of queried individually.

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• Post Crosstalk 2012

  - by David Dorf

  This year the Oracle Retail users conference, Crosstalk, had a 20% increase in attendees, which was driven by both new customers and those acquired via Endeca.  As the product assets of Oracle have grown, so has the completeness of the solution set.  This year was marked by the breadth of omni-channel stories. Rose Spicer and her marketing team (see photo on left) always strive for an equal balance of retailer presentations, networking opportunities, and unique experiences -- this year was no exception.  We had 41 different retailers from China, Russia, South Africa, Brazil, Chile, US, Canada and the UK sharing their insights with one another. In all there were 251 executives from 120 iconic brands such as Daphne, Kohl's, Morrisons, Abercrombie & Fitch, Hot Topic, Talbots, Petco, Deckers, Sportmaster, Mr. Price, Falabella, and Disney to name a few. From a product perspective, there were a few new developments from Oracle Retail: Endeca's search engine has been integrated into the ATG commerce platform. The latest Retail Analytics application, Oracle Retail Customer Analytics, is generally available. Oracle Retail previewed a new fully-integrated mobile POS. But the real benefit of attending Crosstalk was hearing about the experiences of retailers and partners.  Here are are a few interesting facts I picked up: At Kohl's, the most popular website accessed by customers within their stores is Facebook.  With all the buzz about showrooming, I was really expecting it to be Amazon. Daphne, a Chinese shoe retailer, is opening 3 new stores per day.  Being located near the factories allows them to have a very agile supply chain as well. Disney Stores have increased sales by 25% at stores upgraded to include Mobile POS.  They continue to lead the pack with excellent customer experiences. Quicksilver reported that 1 in 5 visits to their website comes from a tablet.  More evidence that tablets are replacing traditional PCs in households. By tagging shoes with RFID, Saks is able to ensure all shoe models are on display.  If a model is not being displayed, it has no chance of being sold. Additionally, there were awards, store tours on Michigan Avenue, fireworks at Navy Pier, and the Oracle Retail house band, Bolo313, performing at Solider Field.  Speaking of which, a few retailers got on stage and jammed with band -- possible rival to Rock & Roll Retail? You can always find the latest info from us at the Retail Rack. The next events on tap are the Partner Summit followed by OpenWorld.

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• Retail in New York - a walk down 5th Avenue

  - by sarah.taylor(at)oracle.com

  It's the week of the NRF Big Show and all eyes in the retail industry are on New York. The Big Apple is famous for Big Retail -with a proliferation of incredibly iconic stores. The environment is exciting and familiar even to people visiting this small island for the first time. Most of us have travelled down Fifth Avenue watching movies and TV even if we have never set foot on American soil. I find it one of the most exciting retail cities in the world and I am thrilled this year to be here with so many of Oracle's International retail customers who are joining us for the Retail Exchange. The Oracle program brings retailers from all over the planet together to share ideas and be inspired by New York retail and the NRF event. The show celebrates its 100th year in 2011 and New York itself has been recognized globally as the capital of innovative retail for just as long.  Fifth Avenue is where many global brands have placed their flagship stores, and businesses are in constant competition to set themselves apart from their competitors - both in the store and from the street.  These flag ship retail destinations present what today's customers are finding most exciting and delightful about retail. For the tourist market, they may only visit these stores once, but the impression that a trip to a flagship store leaves with a customer can last a lifetime.  One of the stores that is currently turning heads on Fifth Avenue is Hollister, sister brand to Abercrombie and Fitch, which has filled its shop front with a massive live video (and audio) feed of surfers on the beach in California.  To complete the effect, they also have troughs of water in front of the video screens to bring the sea to the street.  And this isn't the only kind of surfing that retailers are considering today and multi-channel retail is a hot topic that all of the retailers joining the Retail Exchange are considering.   The rest of the world looks to the brands along Fifth Avenue for inspiration - how they take advantage of new opportunities, how they set themselves apart from their competitors and how they keep their products fresh and desirable. With these inspiring pioneers in New York, it's little wonder that NRF's Big Show is so popular, and that New York is viewed as one of the retail capitals of the world. It is a pleasure to be here with so many of the world's greatest international retailers.

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• Do you keep your ideas secret? and why?

  - by MainMa

  I believe any programmer has several ideas that she/he considers as innovative or at least valuable. It may be an idea of a new product which will make this world better or a new development approach, etc. But a great idea must be implemented and promoted/advertised. This requires a lot of work (proofs of concept, prototypes, technology previews, etc.) and a lot of money (appropriate advertisement, marketing, etc.). So months later, the idea stays in our heads, but nothing else is done, because it's difficult, long and expensive, sometimes even impossible for a single developer. On the other hand, it would be painful to share our ideas, and see a medium-size company which has enough resources making something useful from it and having success and money. So what do you do with your ideas you can hardly implement or patent? Do you talk freely about them in discussion boards and with other developers? Do you keep them like a precious thing without never talking about them to anybody? If you keep your ideas, why are you doing so? Is it just because you hope that one day, you will be able to implement them and have a huge success, while you know very well by experience that it's an utopia?

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• Why is math taught "backwards"? [closed]

  - by Yorirou

  A friend of mine showed me a pretty practical Java example. It was a riddle. I got excited and quickly solved the problem. After it, he showed me the mathematical explanation of my solution (he proved why is it good), and it was completely clear for me. This seems like natural approach for me: solve problems, and generalize. This is very familiar to me, I do it all the time when I am programming: I write a function. When I have to write a similar function, I generalize the problem, grab the generic parts, and refactor them to a function, and solve the original problems as a specialization of the general function. At the university (or at least where I study), things work backwards. The professors shows just the highest possible level of the solutions ("cryptic" mathematical formulas). My problem is that this is too abstract for me. There is no connection of my previous knowledge (== reality in my sense), so even if I can understand it, I can't really learn it properly. Others are learning these formulas word-by-word, and get good grades, since they can write exactly the same to the test, but this is not an option for me. I am a curious person, I can learn interesting things, but I can't learn just text. My brain is for storing toughts, not strings. There are proofs for the theories, but they are also really hard to understand because of this, and in most of the cases they are omitted. What is the reason for this? I don't understand why is it a good idea to show the really high level of abstraction and then leave the practical connections (or some important ideas / practical motivations) out?

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