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  • A Simulator for a non-deterministic Push-Down Automaton

    - by shake
    Well, i need to make simulator for non-deterministic Push-Down Automaton. Everything is okey, i know i need to do recursion or something similar. But i do not know how to make that function which would simulate automaton. I got everything else under control, automaton generator, stack ... I am doing it in java, so this is maybe only issue that man can bump on, and i did it. So if anyone have done something similar, i could use advices. This is my current organisation of code: C lasses: class transit: list -contains non deterministic transitions state input sign stack sign class generator it generate automaton from file clas NPA public boolean start() - this function i am having trouble with Of course problem of separate stacks, and input for every branch. I tried to solve it with collection of objects NPA and try to start every object, but it doesn work :((..

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  • Do invariant assertions fit into C# programming?

    - by P.Brian.Mackey
    In the book coders at work, the author asks "How do you use invariants in your code". Please explain what this question means. I saw class invariants on wiki, but the example is in Java and I am not skilled enough in Java to relate this example to C#. .NET 4.0 introduces invariance, covariance, and contravariance and is well explained here. Invariance is so broad. The authors usage of the word seems unit test related. For those that read the book, what does the author mean? Are we talking about making an assumption and simply testing the validity after the unit test?

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  • After adding data files to a file group Is there a way to distribute the data into the new files?

    - by Blootac
    I have a database in a single file group, with a single file group. I've added 7 data files to this file group. Is there a way to rebalance the data over the 8 data files other than by telling sql server to empty the original? If this is the only way, is it possible to allow sql server to start writing to this file? MSDN says that once its empty its marked so no new data will be written to it. What I'm aiming for is 8 equally balanced data files. I'm running SQL Server 2005 standard edition. Thanks

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  • What problems have you solved using constraint programming?

    - by knorv
    I'd like to know about specific problems you - the SO reader - have solved using constraint programming and what constraint logic language you used. Questions: What problems have you used constraint programming to solve? What constraint logic language did you use? I'm looking for first-hand experiences, so please do not answer unless you have that.

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  • What is better for a student programming in C++ to learn for writing GUI: C# vs QT?

    - by flashnik
    I'm a teacher(instructor) of CS in the university. The course is based on Cormen and Knuth and students program algorithms in C++. But sometimes it is good to show how an algorithm works or just a result of task through GUI. Also in my opinion it's very imporant to be able to write full programs. They will have courses concerning GUI but a three years, later, in fact, before graduatuion. I think that they should be able to write simple GUI applications earlier. So I want to teach them it. How do you think, what is more useful for them to learn: programming GUI with QT or writing GUI in C# and calling unmanaged C++ library?

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  • CSC folder data access AND roaming profiles issues (Vista with Server 2003, then 2008)

    - by Alex Jones
    I'm a junior sysadmin for an IT contractor that helps small, local government agencies, like little towns and the like. One of our clients, a public library with ~ 50 staff users, was recently migrated from Server 2003 Standard to Server 2008 R2 Standard in a very short timeframe; our senior employee, the only network engineer, had suddenly put in his two weeks notice, so management pushed him to do this project before quitting. A bit hasty on management's part? Perhaps. Could we do anything about that? Nope. Do I have to fix this all by myself? Pretty much. The network is set up like this: a) 50ish staff workstations, all running Vista Business SP2. All staff use MS Outlook, which uses RPC-over-HTTPS ("Outlook Anywhere") for cached Exchange access to an offsite location. b) One new (virtualized) Server 2008 R2 Standard instance, running atop a Server 2008 R2 host via Hyper-V. The VM is the domain's DC, and also the site's one and only file server. Let's call that VM "NEWBOX". c) One old physical Server 2003 Standard server, running the same roles. Let's call it "OLDBOX". It's still on the network and accessible, but it's been demoted, and its shares have been disabled. No data has been deleted. c) Gigabit Ethernet everywhere. The organization's only has one domain, and it did not change during the migration. d) Most users were set up for a combo of redirected folders + offline files, but some older employees who had been with the organization a long time are still on roaming profiles. To sum up: the servers in question handle user accounts and files, nothing else (eg, no TS, no mail, no IIS, etc.) I have two major problems I'm hoping you can help me with: 1) Even though all domain users have had their redirected folders moved to the new server, and loggin in to their workstations and testing confirms that the Documents/Music/Whatever folders point to the new paths, it appears some users (not laptops or anything either!) had been working offline from OLDBOX for a long time, and nobody realized it. Here's the ugly implication: a bunch of their data now lives only in their CSC folders, because they can't access the share on OLDBOX and sync with it finally. How do I get this data out of those CSC folders, and onto NEWBOX? 2) What's the best way to migrate roaming profile users to non-roaming ones, without losing vital data like documents, any lingering PSTs, etc? Things I've thought about trying: For problem 1: a) Reenable the documents share on OLDBOX, force an Offline Files sync for ALL domain users, then copy OLDBOX's share's data to the equivalent share on NEWBOX. Reinitialize the Offline Files cache for every user. With this: How do I safely force a domain-wide Offline Files sync? Could I lose data by reenabling the share on OLDBOX and forcing the sync? Afterwards, how can I reinitialize the Offline Files cache for every user, without doing it manually, workstation by workstation? b) Determine which users have unsynced changes to OLDBOX (again, how?), search each user's CSC folder domain-wide via workstation admin shares, and grab the unsynched data. Reinitialize the Offline Files cache for every user. With this: How can I detect which users have unsynched changes with a script? How can I search each user's CSC folder, when the ownership and permissions set for CSC folders are so restrictive? Again, afterwards, how can I reinitialize the Offline Files cache for every user, without doing it manually, workstation by workstation? c) Manually visit each workstation, copy the contents of the CSC folder, and manually copy that data onto NEWBOX. Reinitialize the Offline Files cache for every user. With this: Again, how do I 'break into' the CSC folder and get to its data? As an experiment, I took one workstation's HD offsite, imaged it for safety, and then tried the following with one of our shop PCs, after attaching the drive: grant myself full control of the folder (failed), grant myself ownership of the folder (failed), run chkdsk on the whole drive to make sure nothing's messed up (all OK), try to take full control of the entire drive (failed), try to take ownership of the entire drive (failed) MS KB articles and Googling around suggests there's a utility called CSCCMD that's meant for this exact scenario...but it looks like it's available for XP, not Vista, no? Again, afterwards, how can I reinitialize the Offline Files cache for every user, without doing it manually, workstation by workstation? For problem 2: a) Figure out which users are on roaming profiles, and where their profiles 'live' on the server. Create new folders for them in the redirected folders repository, migrate existing data, and disable the roaming. With this: Finding out who's roaming isn't hard. But what's the best way to disable the roaming itself? In AD Users and Computers, or on each user's workstation? Doing it centrally on the server seems more efficient; that said, all of the KB research I've done turns up articles on how to go from local to roaming, not the other way around, so I don't have good documentation on this. In closing: we have good backups of NEWBOX and OLDBOX, but not of the workstations themselves, so anything drastic on the client side would need imaging and testing for safety. Thanks for reading along this far! Hopefully you can help me dig us out of this mess.

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  • Specifying Language for a grammar

    - by darkie15
    Hi All, Is there any specific methodology followed to specify a language for given grammar ?? i.e. Is it necessary to run all the production rules given in a grammar to determine the language it represents? I don't have an example as such since the one I am working on is a homework question. Regards, darkie15

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  • How does a custom accessor method implementation in Core Data look like?

    - by dontWatchMyProfile
    The documentation is pretty confusing on this one: The implementation of accessor methods you write for subclasses of NSManagedObject is typically different from those you write for other classes. If you do not provide custom instance variables, you retrieve property values from and save values into the internal store using primitive accessor methods. You must ensure that you invoke the relevant access and change notification methods (willAccessValueForKey:, didAccessValueForKey:, willChangeValueForKey:, didChangeValueForKey:, willChangeValueForKey:withSetMutation:usingObjects:, and didChangeValueForKey:withSetMutation:usingObjects:). NSManagedObject disables automatic key-value observing (KVO, see Key-Value Observing Programming Guide) change notifications, and the primitive accessor methods do not invoke the access and change notification methods. In accessor methods for properties that are not defined in the entity model, you can either enable automatic change notifications or invoke the appropriate change notification methods. Are there any examples that show how these look like?

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  • What does it mean to do/determine something "programmatically"?

    - by Chris Lutz
    Programmatically. (alt. programmically) I've never used it, but I see it in questions a lot, i.e. "How to programmatically determine [insert task here]". Firefox immediately tells me that neither of these two words are real (at least, it doesn't recognize them). I've also never seen them used anywhere but here. 1) What does it mean to do/determine something "programmatically"? 2) Why do so many people ask how to do/determine something "programmatically"? Isn't it assumed that, if you're asking how to do something on a programming help board, you're asking how to do it "programmatically"? 3) Why is it that I've never seen the word "programmatically" anywhere else?

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  • Learning material on SAT (Boolean Satisfiability Problem)

    - by Jules
    What are good documents to read on SAT (Boolean satisfiability problem) solvers. I have not been able to find good material via Google. The documents I found were either birds eye view, too advanced or corrupted PDF files... Which papers/documents do you recommend to learn about the algorithms in modern practical SAT solvers?

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  • What should i do for accomodating large scale data storage and retrieval?

    - by kailashbuki
    There's two columns in the table inside mysql database. First column contains the fingerprint while the second one contains the list of documents which have that fingerprint. It's much like an inverted index built by search engines. An instance of a record inside the table is shown below; 34 "doc1, doc2, doc45" The number of fingerprints is very large(can range up to trillions). There are basically following operations in the database: inserting/updating the record & retrieving the record accoring to the match in fingerprint. The table definition python snippet is: self.cursor.execute("CREATE TABLE IF NOT EXISTS `fingerprint` (fp BIGINT, documents TEXT)") And the snippet for insert/update operation is: if self.cursor.execute("UPDATE `fingerprint` SET documents=CONCAT(documents,%s) WHERE fp=%s",(","+newDocId, thisFP))== 0L: self.cursor.execute("INSERT INTO `fingerprint` VALUES (%s, %s)", (thisFP,newDocId)) The only bottleneck i have observed so far is the query time in mysql. My whole application is web based. So time is a critical factor. I have also thought of using cassandra but have less knowledge of it. Please suggest me a better way to tackle this problem.

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  • Is it bad practice to use an enum that maps to some seed data in a Database?

    - by skb
    I have a table in my database called "OrderItemType" which has about 5 records for the different OrderItemTypes in my system. Each OrderItem contains an OrderItemType, and this gives me referential integrity. In my middletier code, I also have an enum which matches the values in this table so that I can have business logic for the different types. My dev manager says he hates it when people do this, and I am not exactly sure why. Is there a better practice I should be following?

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  • P-NP-Problem: What are the most promising methods?

    - by phimuemue
    Hello everybody, I know that P=NP has not been solved up to now, but can anybody tell me something about the following: What are currently the most promising mathematical / computer scientific methods that could be helpful to tackle this problem? Or are there even none such methods known to be potentially helpful up to now? Is there any (free) compendium on this topic where I can find all / most of the research done in this area?

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  • How do you avoid an invalid search space in a genetic algorithm?

    - by Dave
    I am developing a GA for a school project and I've noticed that upon evaluating my functions for fitness, an individual is equivalent to its inverse. For example, the set (1, 1, -1, 1) is equivalent to (-1, -1, 1, -1). To shrink my search space and reach a solution more efficiently, how can I avoid my crossovers from searching in this second half of the search space?

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  • Approximate timings for various operations on a "typical desktop PC" anno 2010

    - by knorv
    In the article "Teach Yourself Programming in Ten Years" Peter Norvig (Director of Research, Google) gives the following approximate timings for various operations on a typical 1GHz PC back in 2001: execute single instruction = 1 nanosec = (1/1,000,000,000) sec fetch word from L1 cache memory = 2 nanosec fetch word from main memory = 10 nanosec fetch word from consecutive disk location = 200 nanosec fetch word from new disk location (seek) = 8,000,000 nanosec = 8 millisec What would the corresponding timings be for your definition of a typical PC desktop anno 2010?

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  • Mutual Information / Entropy Calculation Help

    - by Fillip
    Hi, Hoping someone can give me some pointers with this entropy problem. Say X is chosen randomly from the uniform integer distribution 0-32 (inclusive). I calculate the entropy, H(X) = 32 bits, as each Xi has equal probability of occurring. Now, say the following pseudocode executes. int r = rand(0,1); // a random integer 0 or 1 r = r * 33 + X; How would I work out the mutual information between the two variables r and X? Mutual Information is defined as I(X; Y) = H(X) - H(X|Y) but I don't really understand how to apply the conditional entropy H(X|Y) to this problem. Thanks

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  • How to get user input for 2 digit data

    - by oneMinute
    In a HTML form user is expect to fill / select some data and trigger an action probably a http-post. If your only requested data field is a "2 digit" you can use html text input element get some data. Then you want to make it useful; enable user easily select data from a 'html select' But not all of your data is well-ordered so eye-searching within these data is somehow cumbersome. Because your data is meaningful with its relations. If there is no primary key for foreign key "12" it should not be shown. Vice versa if this foreign key occurs a lot, then it has some weight and could be displayed with more importance. So, what will be your way? a) Use text input to get data and validate it with regex, javascript, ... b) Use some dropdown select. c) Any other way ? Any answer will appreciated :)

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  • Task vs. process, is there really any difference?

    - by DASKAjA
    Hi there, I'm studying for my final exams in my CS major on the subject distributed systems and operating systems. I'm in the need for a good definition for the terms task, process and threads. So far I'm confident that a process is the representation of running (or suspended, but initiated) program with its own memory, program counter, registers, stack, etc (process control block). Processes can run threads which share memory, so that communication via shared memory is possible in contrast to processes which have to communicate via IPC. But what's the difference between tasks and process. I often read that they're interchangable and that the term task isn't used anymore. Is that really true?

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  • Learning networking fundamentals

    - by bplus
    Not having a CS degree has left large holes in my programming related knowledge. In particular I'd really like to learn some of the computer networking stuff I would have got in a good CS degree. The problem I really have is "not knowing what I don't know". So far I know I don't know anything about the following (as far as computer networks are concearned) -sockets -ports -internet protocol (the whole IP stack I keep hearing about). Can anyone add more to the list? Can anyone suggest a project (writing a toy web server?) Thanks in advance

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  • What are alternatives to standard ORM in a data access layer?

    - by swampsjohn
    We're all familiar with basic ORM with relational databases: an object corresponds to a row and an attribute in that object to a column (or some slight variation), though many ORMs add a lot of bells and whistles. I'm wondering what other alternatives there are (besides raw access to the database or whatever you're working with). Alternatives that just work with relational databases would be great, but ones that could encapsulate multiple types of backends besides just SQL (such as flat files, RSS, NoSQL, etc.) would be even better. I'm more interested in ideas rather than specific implantations and what languages/platforms they work with, but please link to anything you think is interesting.

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  • Are .NET's regular expressions Turing complete?

    - by Robert
    Regular expressions are often pointed to as the classical example of a language that is not Turning complete. For example "regular expressions" is given in as the answer to this SO question looking for languages that are not Turing complete. In my, perhaps somewhat basic, understanding of the notion of Turning completeness, this means that regular expressions cannot be used check for patterns that are "balanced". Balanced meaning have an equal number of opening characters as closing characters. This is because to do this would require you to have some kind of state, to allow you to match the opening and closing characters. However the .NET implementation of regular expressions introduces the notion of a balanced group. This construct is designed to let you backtrack and see if a previous group was matched. This means that a .NET regular expressions: ^(?<p>a)*(?<-p>b)*(?(p)(?!))$ Could match a pattern that: ab aabb aaabbb aaaabbbb ... etc. ... Does this means .NET's regular expressions are Turing complete? Or are there other things that are missing that would be required for the language to be Turing complete?

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  • Base64 Encoded Data - DB or Filesystem

    - by Marty
    I have a new program that will be generating a lot of Base64 encoded audio and image data. This data will be served via HTTP in the form of XML and the Base64 data will be inline. These files will most likely break 20MB and higher. Would it be more efficient to serve these files directly from the filesystem or would it be feasible to store the data in a MySQL database? Caching will be set up but overall unnecessary because it is likely that this data will be purged shortly after it is created and served. i know that storing binary data in the DB is frowned upon in most circumstances but since this will all be character data I want to see what the consensus is. As of now, I am leaning toward storing them in the filesystem for efficiency reasons but if it is feasible to store them in a database it would be much easier to manage the data.

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  • Repartition hard drive using Mac OS X, keep existing data

    - by Jonny
    I got a 1 TB disk a year or so ago and loaded it with some hundred of GB of data. I somehow neglected to check the file system, which turns out to be FAT-32 and thus too small for files bigger than 4 GB. So now I want to change it, without deleting the data. I thought I'd just make a new partition in the so far unused space. Then with the new partition, copy/move the data into the new partition, and then delete the old FAT-32 partition, and make the new partition bigger again... or just make a few more partitions. The critical step here is, can I make that new partition without ruining the data? The data should be fairly sequentially added to the start of the disk, but what do I know... so that's why I'm asking. Can I safely use Disk Utility for this? Any recommended file system?

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