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  • Password recovery toolkit

    - by John Craggs
    I am using Wise Password Recover 2009 and basically satisfied with its wide compatibility. But it gets failed in retrieving one of my outlook accounts. Is there any other password recovery toolkit can do the recovery for me?

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  • Web interface to allow users to change their Active Directory password

    - by csexton
    I have a few web applications that use Active Directory to authenticate. What I would like to be able to do is provide a simple web page that would allow users to update their AD password. This wasn't a problem when the majority of the users had windows machines that connected to this AD server (and could ctrl-alt-del to change the password), but we are moving away from that and the AD server is mostly for web apps. Is there a simple solution for this, or am I looking at the big LDAP managers?

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  • Windows 7 - store network password

    - by disserman
    Windows 7 keeps asking for a password every time I mount a webdav. I don't want to store a password in a .bat file because it's so insecure. Is there any way to force system store it? Manually adding credentials in user manager helps storing passwords for SMB shares but for webdav doesn't. btw, as far as I remember, Vista had the same problems.

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  • Changing user password logged in as Admin

    - by Mike
    Quick question, I forgot my Win XP password to logon to my laptop. My user name is on the "Office" domain for work. When I logon as the Administrator I have to logon the local domain "This computer". How do I reset my password for my account on the other domain? Thanks!

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  • How to make password reset disk windows

    - by Mirage
    I don't have floppy drive on my computer. Is there any way that i can make the password reset disk in a folders so that when i lose my passowrd then i can choose that folder to work as password reset disk. Is there any other option available beside Floppy drive

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  • Firefox password autocomplete

    - by mck89
    Hi, i have a problem with Firefox autocomplete in login forms. When i enter a password and a username for the first time it asks me if i want to remember them, i click on "remember" and it saves the data, but when i log out and then return to the login page it shows me nothing. The password is autocompleted only after i enter the username. Is there a way to do the autocomplete immediately like in any other browser?

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  • Double password in Directory Server

    - by xain
    Hi, anybody knows how to implement a second password in an LDAP, so it's policies are different from the userPassword attribute ? The idea is to use it as a non-login password (for instance to "sign" a transaction). Thanks

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  • Removing the password from a PDF file

    - by Alister
    I have a couple of ebooks as PDFs with passwords, however my ebook reader (sony prs600) doesn't seem to support PDFs with passwords. What is the easiest of removing the password from a PDF (I know the password, which presumably helps a lot). It's a bit annoying buying a book and then only being able to read it in front of a computer.

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  • AD Password About to Expire check problem with ASP.Net

    - by Vince
    Hello everyone, I am trying to write some code to check the AD password age during a user login and notify them of the 15 remaining days. I am using the ASP.Net code that I found on the Microsoft MSDN site and I managed to add a function that checks the if the account is set to change password at next login. The login and the change password at next login works great but I am having some problems with the check for the password age. This is the VB.Net code for the DLL file: Imports System Imports System.Text Imports System.Collections Imports System.DirectoryServices Imports System.DirectoryServices.AccountManagement Imports System.Reflection 'Needed by the Password Expiration Class Only -Vince Namespace FormsAuth Public Class LdapAuthentication Dim _path As String Dim _filterAttribute As String 'Code added for the password expiration added by Vince Private _domain As DirectoryEntry Private _passwordAge As TimeSpan = TimeSpan.MinValue Const UF_DONT_EXPIRE_PASSWD As Integer = &H10000 'Function added by Vince Public Sub New() Dim root As New DirectoryEntry("LDAP://rootDSE") root.AuthenticationType = AuthenticationTypes.Secure _domain = New DirectoryEntry("LDAP://" & root.Properties("defaultNamingContext")(0).ToString()) _domain.AuthenticationType = AuthenticationTypes.Secure End Sub 'Function added by Vince Public ReadOnly Property PasswordAge() As TimeSpan Get If _passwordAge = TimeSpan.MinValue Then Dim ldate As Long = LongFromLargeInteger(_domain.Properties("maxPwdAge")(0)) _passwordAge = TimeSpan.FromTicks(ldate) End If Return _passwordAge End Get End Property Public Sub New(ByVal path As String) _path = path End Sub 'Function added by Vince Public Function DoesUserHaveToChangePassword(ByVal userName As String) As Boolean Dim ctx As PrincipalContext = New PrincipalContext(System.DirectoryServices.AccountManagement.ContextType.Domain) Dim up = UserPrincipal.FindByIdentity(ctx, userName) Return (Not up.LastPasswordSet.HasValue) 'returns true if last password set has no value. End Function Public Function IsAuthenticated(ByVal domain As String, ByVal username As String, ByVal pwd As String) As Boolean Dim domainAndUsername As String = domain & "\" & username Dim entry As DirectoryEntry = New DirectoryEntry(_path, domainAndUsername, pwd) Try 'Bind to the native AdsObject to force authentication. Dim obj As Object = entry.NativeObject Dim search As DirectorySearcher = New DirectorySearcher(entry) search.Filter = "(SAMAccountName=" & username & ")" search.PropertiesToLoad.Add("cn") Dim result As SearchResult = search.FindOne() If (result Is Nothing) Then Return False End If 'Update the new path to the user in the directory. _path = result.Path _filterAttribute = CType(result.Properties("cn")(0), String) Catch ex As Exception Throw New Exception("Error authenticating user. " & ex.Message) End Try Return True End Function Public Function GetGroups() As String Dim search As DirectorySearcher = New DirectorySearcher(_path) search.Filter = "(cn=" & _filterAttribute & ")" search.PropertiesToLoad.Add("memberOf") Dim groupNames As StringBuilder = New StringBuilder() Try Dim result As SearchResult = search.FindOne() Dim propertyCount As Integer = result.Properties("memberOf").Count Dim dn As String Dim equalsIndex, commaIndex Dim propertyCounter As Integer For propertyCounter = 0 To propertyCount - 1 dn = CType(result.Properties("memberOf")(propertyCounter), String) equalsIndex = dn.IndexOf("=", 1) commaIndex = dn.IndexOf(",", 1) If (equalsIndex = -1) Then Return Nothing End If groupNames.Append(dn.Substring((equalsIndex + 1), (commaIndex - equalsIndex) - 1)) groupNames.Append("|") Next Catch ex As Exception Throw New Exception("Error obtaining group names. " & ex.Message) End Try Return groupNames.ToString() End Function 'Function added by Vince Public Function WhenExpires(ByVal username As String) As TimeSpan Dim ds As New DirectorySearcher(_domain) ds.Filter = [String].Format("(&(objectClass=user)(objectCategory=person)(sAMAccountName={0}))", username) Dim sr As SearchResult = FindOne(ds) Dim user As DirectoryEntry = sr.GetDirectoryEntry() Dim flags As Integer = CInt(user.Properties("userAccountControl").Value) If Convert.ToBoolean(flags And UF_DONT_EXPIRE_PASSWD) Then 'password never expires Return TimeSpan.MaxValue End If 'get when they last set their password Dim pwdLastSet As DateTime = DateTime.FromFileTime(LongFromLargeInteger(user.Properties("pwdLastSet").Value)) ' return pwdLastSet.Add(PasswordAge).Subtract(DateTime.Now); If pwdLastSet.Subtract(PasswordAge).CompareTo(DateTime.Now) > 0 Then Return pwdLastSet.Subtract(PasswordAge).Subtract(DateTime.Now) Else Return TimeSpan.MinValue 'already expired End If End Function 'Function added by Vince Private Function LongFromLargeInteger(ByVal largeInteger As Object) As Long Dim type As System.Type = largeInteger.[GetType]() Dim highPart As Integer = CInt(type.InvokeMember("HighPart", BindingFlags.GetProperty, Nothing, largeInteger, Nothing)) Dim lowPart As Integer = CInt(type.InvokeMember("LowPart", BindingFlags.GetProperty, Nothing, largeInteger, Nothing)) Return CLng(highPart) << 32 Or CUInt(lowPart) End Function 'Function added by Vince Private Function FindOne(ByVal searcher As DirectorySearcher) As SearchResult Dim sr As SearchResult = Nothing Dim src As SearchResultCollection = searcher.FindAll() If src.Count > 0 Then sr = src(0) End If src.Dispose() Return sr End Function End Class End Namespace And this is the Login.aspx page: sub Login_Click(sender as object,e as EventArgs) Dim adPath As String = "LDAP://DC=xxx,DC=com" 'Path to your LDAP directory server Dim adAuth As LdapAuthentication = New LdapAuthentication(adPath) Try If (True = adAuth.DoesUserHaveToChangePassword(txtUsername.Text)) Then Response.Redirect("passchange.htm") ElseIf (True = adAuth.IsAuthenticated(txtDomain.Text, txtUsername.Text, txtPassword.Text)) Then Dim groups As String = adAuth.GetGroups() 'Create the ticket, and add the groups. Dim isCookiePersistent As Boolean = chkPersist.Checked Dim authTicket As FormsAuthenticationTicket = New FormsAuthenticationTicket(1, _ txtUsername.Text, DateTime.Now, DateTime.Now.AddMinutes(60), isCookiePersistent, groups) 'Encrypt the ticket. Dim encryptedTicket As String = FormsAuthentication.Encrypt(authTicket) 'Create a cookie, and then add the encrypted ticket to the cookie as data. Dim authCookie As HttpCookie = New HttpCookie(FormsAuthentication.FormsCookieName, encryptedTicket) If (isCookiePersistent = True) Then authCookie.Expires = authTicket.Expiration End If 'Add the cookie to the outgoing cookies collection. Response.Cookies.Add(authCookie) 'Retrieve the password life Dim t As TimeSpan = adAuth.WhenExpires(txtUsername.Text) 'You can redirect now. If (passAge.Days = 90) Then errorLabel.Text = "Your password will expire in " & DateTime.Now.Subtract(t) 'errorLabel.Text = "This is" 'System.Threading.Thread.Sleep(5000) Response.Redirect("http://somepage.aspx") Else Response.Redirect(FormsAuthentication.GetRedirectUrl(txtUsername.Text, False)) End If Else errorLabel.Text = "Authentication did not succeed. Check user name and password." End If Catch ex As Exception errorLabel.Text = "Error authenticating. " & ex.Message End Try End Sub ` Every time I have this Dim t As TimeSpan = adAuth.WhenExpires(txtUsername.Text) enabled, I receive "Arithmetic operation resulted in an overflow." during the login and won't continue. What am I doing wrong? How can I correct this? Please help!! Thank you very much for any help in advance. Vince

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  • Suggest a good method with least lookup time complexity

    - by Amrish
    I have a structure which has 3 identifier fields and one value field. I have a list of these objects. To give an analogy, the identifier fields are like the primary keys to the object. These 3 fields uniquely identify an object. Class { int a1; int a2; int a3; int value; }; I would be having a list of say 1000 object of this datatype. I need to check for specific values of these identity key values by passing values of a1, a2 and a3 to a lookup function which would check if any object with those specific values of a1, a2 and a3 is present and returns that value. What is the most effective way to implement this to achieve a best lookup time? One solution I could think of is to have a 3 dimensional matrix of length say 1000 and populate the value in it. This has a lookup time of O(1). But the disadvantages are. 1. I need to know the length of array. 2. For higher identity fields (say 20), then I will need a 20 dimension matrix which would be an overkill on the memory. For my actual implementation, I have 23 identity fields. Can you suggest a good way to store this data which would give me the best look up time?

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  • How should I change my Graph structure (very slow insertion)?

    - by Nazgulled
    Hi, This program I'm doing is about a social network, which means there are users and their profiles. The profiles structure is UserProfile. Now, there are various possible Graph implementations and I don't think I'm using the best one. I have a Graph structure and inside, there's a pointer to a linked list of type Vertex. Each Vertex element has a value, a pointer to the next Vertex and a pointer to a linked list of type Edge. Each Edge element has a value (so I can define weights and whatever it's needed), a pointer to the next Edge and a pointer to the Vertex owner. I have a 2 sample files with data to process (in CSV style) and insert into the Graph. The first one is the user data (one user per line); the second one is the user relations (for the graph). The first file is quickly inserted into the graph cause I always insert at the head and there's like ~18000 users. The second file takes ages but I still insert the edges at the head. The file has about ~520000 lines of user relations and takes between 13-15mins to insert into the Graph. I made a quick test and reading the data is pretty quickly, instantaneously really. The problem is in the insertion. This problem exists because I have a Graph implemented with linked lists for the vertices. Every time I need to insert a relation, I need to lookup for 2 vertices, so I can link them together. This is the problem... Doing this for ~520000 relations, takes a while. How should I solve this? Solution 1) Some people recommended me to implement the Graph (the vertices part) as an array instead of a linked list. This way I have direct access to every vertex and the insertion is probably going to drop considerably. But, I don't like the idea of allocating an array with [18000] elements. How practically is this? My sample data has ~18000, but what if I need much less or much more? The linked list approach has that flexibility, I can have whatever size I want as long as there's memory for it. But the array doesn't, how am I going to handle such situation? What are your suggestions? Using linked lists is good for space complexity but bad for time complexity. And using an array is good for time complexity but bad for space complexity. Any thoughts about this solution? Solution 2) This project also demands that I have some sort of data structures that allows quick lookup based on a name index and an ID index. For this I decided to use Hash Tables. My tables are implemented with separate chaining as collision resolution and when a load factor of 0.70 is reach, I normally recreate the table. I base the next table size on this http://planetmath.org/encyclopedia/GoodHashTablePrimes.html. Currently, both Hash Tables hold a pointer to the UserProfile instead of duplication the user profile itself. That would be stupid, changing data would require 3 changes and it's really dumb to do it that way. So I just save the pointer to the UserProfile. The same user profile pointer is also saved as value in each Graph Vertex. So, I have 3 data structures, one Graph and two Hash Tables and every single one of them point to the same exact UserProfile. The Graph structure will serve the purpose of finding the shortest path and stuff like that while the Hash Tables serve as quick index by name and ID. What I'm thinking to solve my Graph problem is to, instead of having the Hash Tables value point to the UserProfile, I point it to the corresponding Vertex. It's still a pointer, no more and no less space is used, I just change what I point to. Like this, I can easily and quickly lookup for each Vertex I need and link them together. This will insert the ~520000 relations pretty quickly. I thought of this solution because I already have the Hash Tables and I need to have them, then, why not take advantage of them for indexing the Graph vertices instead of the user profile? It's basically the same thing, I can still access the UserProfile pretty quickly, just go to the Vertex and then to the UserProfile. But, do you see any cons on this second solution against the first one? Or only pros that overpower the pros and cons on the first solution? Other Solution) If you have any other solution, I'm all ears. But please explain the pros and cons of that solution over the previous 2. I really don't have much time to be wasting with this right now, I need to move on with this project, so, if I'm doing to do such a change, I need to understand exactly what to change and if that's really the way to go. Hopefully no one fell asleep reading this and closed the browser, sorry for the big testament. But I really need to decide what to do about this and I really need to make a change. P.S: When answering my proposed solutions, please enumerate them as I did so I know exactly what are you talking about and don't confuse my self more than I already am.

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  • Can you figure out the password hashing scheme?

    - by Adal
    I have two passwords and two resulting hashes. I can't figure out how the hash is derived from the password. I don't know if salting is used. I don't know if the password is hashed as a integer value or as a string (possibly Unicode). Password: 6770 Hash: c12114b91a3841c143bbeb121693e80b Password: 9591 Hash: 25238d578b6a61c2c54bfe55742984c1 The hash length seems to suggest MD5. Anybody has any ideas what I could try? Note: This is not for hacking purposes. I'm trying to access a service through an API instead of it's desktop client, and I can't figure out how to compute the password hash. Currently instead of using my real password I'm sending directly the hash.

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  • Time complexity to fill hash table (homework)?

    - by Heathcliff
    This is a homework question, but I think there's something missing from it. It asks: Provide a sequence of m keys to fill a hash table implemented with linear probing, such that the time to fill it is minimum. And then Provide another sequence of m keys, but such that the time fill it is maximum. Repeat these two questions if the hash table implements quadratic probing I can only assume that the hash table has size m, both because it's the only number given and because we have been using that letter to address a hash table size before when describing the load factor. But I can't think of any sequence to do the first without knowing the hash function that hashes the sequence into the table. If it is a bad hash function, such that, for instance, it hashes every entry to the same index, then both the minimum and maximum time to fill it will take O(n) time, regardless of what the sequence looks like. And in the average case, where I assume the hash function is OK, how am I suppossed to know how long it will take for that hash function to fill the table? Aren't these questions linked to the hash function stronger than they are to the sequence that is hashed? As for the second question, I can assume that, regardless of the hash function, a sequence of size m with the same key repeated m-times will provide the maximum time, because it will cause linear probing from the second entry on. I think that will take O(n) time. Is that correct? Thanks

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  • hash password in SQL Server (asp.net)

    - by ile
    Is this how hashed password stored in SQL Server should look like? This is function I use to hash password (I found it in some tutorial) public string EncryptPassword(string password) { //we use codepage 1252 because that is what sql server uses byte[] pwdBytes = Encoding.GetEncoding(1252).GetBytes(password); byte[] hashBytes = System.Security.Cryptography.MD5.Create().ComputeHash(pwdBytes); return Encoding.GetEncoding(1252).GetString(hashBytes); } EDIT I tried to use sha-1 and now strings seem to look like as they are suppose to: public string EncryptPassword(string password) { return FormsAuthentication.HashPasswordForStoringInConfigFile(password, "sha1"); } // example output: 39A43BDB7827112409EFED3473F804E9E01DB4A8 Result from the image above looks like broken string, but this sha-1 looks normal.... Will this be secure enough?

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  • Recover windows cached domain password

    - by theguy
    I have a computer from another small organization that works with our school. It was previously joined to another domain from elsewhere. The organization doesn't have an IT person so they didn't think of what they needed to do about the information on the computer before they moved it to our school. The previous user of the computer is no longer with the organization so no information about the password. The computer has information that needs to be accessed and programs so putting the hard drive on another computer and grabbing the information is a no go as I need the computer itself to be working as well. The computer is running Windows Vista Business Edition and is joined to a domain with a cached profile. The admin accounts are disabled by GPO. I've been asked to see if I could recover the password but running ophcrack gave me no hits on the cached profile. I'm not too familiar with password recovery tools that would work on a cached profile from a domain so I'm looking for answers here. Any other suggestions? Preferably something free as we're a small school and an easy to use liveCD solution like ophcrack would be appreciated.

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  • O(N log N) Complexity - Similar to linear?

    - by gav
    Hey All, So I think I'm going to get buried for asking such a trivial but I'm a little confused about something. I have implemented quicksort in Java and C and I was doing some basic comparissons. The graph came out as two straight lines, with the C being 4ms faster than the Java counterpart over 100,000 random integers. The code for my tests can be found here; android-benchmarks I wasn't sure what an (n log n) line would look like but I didn't think it would be straight. I just wanted to check that this is the expected result and that I shouldn't try to find an error in my code. I stuck the formula into excel and for base 10 it seems to be a straight line with a kink at the start. Is this because the difference between log(n) and log(n+1) increases linearly? Thanks, Gav

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  • Complexity of subset product

    - by threenplusone
    I have a set of numbers produced using the following formula with integers 0 < x < a. f(x) = f(x-1)^2 % a For example starting at 2 with a = 649. {2, 4, 16, 256, 636, 169, 5, 25, 649, 576, 137, ...} I am after a subset of these numbers that when multiplied together equals 1 mod N. I believe this problem by itself to be NP-complete (based on similaries to Subset-Sum problem). However starting with any integer (x) gives the same solution pattern. Eg. a = 649 {2, 4, 16, 256, 636, 169, 5, 25, 649, 576, 137, ...} = 16 * 5 * 576 = 1 % 649 {3, 9, 81, 71, 498, 86, 257, 500, 135, 53, 213, ...} = 81 * 257 * 53 = 1 % 649 {4, 16, 256, 636, 169, 5, 25, 649, 576, 137, 597, ...} = 256 * 25 * 137 = 1 % 649 I am wondering if this additional fact makes this problem solvable faster? Or if anyone has run into this problem previously or has any advice?

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  • When trying to install Wine on 12.10, 'Sudo' command will not let me type in a password.

    - by Nocturnus
    As the title explains, I have been attempting to install Wine on my laptop which is running 12.10. When I access the command terminal and entered "sudo add-apt-repository ppa:ubuntu-wine/ppa" I was of course met by a password block, when I attempted to enter my password, it flat out wouldn't let me type anything, the only key that got a response from the terminal was "enter" which was met by "incorrect password". To bypass this issue I backed out and used the 'Gksudo' command, this new dialogue box seemed to give me access to sudo commands. I then entered "sudo apt-get update" and "sudo apt-get install wine1.5". Up until the installation everything went fine, but after entering the final command (still using gksudo) The terminal read "the following packages have unmet dependencies" and proceeded to list a bunch of "recommends" So my guess is that Wine hasn't been updated to run on 12.10... Is this true, and is there any other way to open .exe's? Also what was with that funky password misshap? I'm totally new to Ubuntu so I've just been using support pages and tutorials, sorry if I'm a bit naive in these matters...

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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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