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• Using Closure Properties to prove Regularity

  - by WATWF

  Here's a homework problem: Is L_4 Regular? Let L_4 = L*, where L={0^i1^i | i>=1}. I know L is non-regular and I know that Kleene Star is a closed operation, so my assumption is that L_4 is non-regular. However my professor provided an example of the above in which L = {0^p | p is prime}, which he said was regular by proving that L* was equal to L(000* + e) by saying each was a subset of one another (e in this case means the empty word). So his method involved forming a regex of 0^p, but how I can do that when I essentially have one already?

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• What's the best way to test SQL Server connection programmatically?

  - by backslash17

  I need to develop a single routine that will be fired each 5 minutes to check if a list of SQL Servers (10 to 12) are up and running. I can try to obtain a simple query in each one of the servers but this means that I have to create a table, view or stored procedure in every server, even if I use any already made SP I need to have a registered user in each server too. The servers are not in the same physical location so having those requirements would be a complex task. Is there a way to simply "ping" from C# one SQL Server? Thanks in advance!

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• Maven2 junit timeout annotation doesn't work

  - by roesslerj

  We have a bunch of tests in a maven2 project and build with cruisecontrol. However the build regularly hangs, because the annotation of the test with a timeout @Test(timeout = 5000) is ignored. I tried and run maven locally, reproducing the fact, that the timeout is ignored. Is there a way to activate the timeout for the tests again? I currently use a work arround in setting a timeout in cruisecontrol. However this simply means that the whole build is chancelled, and not just the tests that should fail. Remark: It seems in maven 1 there was a property to activate the junit timeout which is missing in maven 2.

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• Best way to track impressions/clicks in a bespoke advertisement system?

  - by Martin Bean

  I've been asked to create a bespoke advertisement system despite suggesting open source alternatives such as OpenX and DoubleClick for Publishers (the former Google Ad Manager). I've got the basics of the system set up, i.e. uploading creatives, creating positions and a mechanism to place creatives within positions; however, the area I'm stuck with is impression and click tracking. At the moment an impression and click is stored with the creative, but this then means impressions/clicks can't be queried. For example, we can't find how many impressions were in position x between date y and date z. How would I go about storing that kind of data? My theory was store the creative ID, position ID and timestamp in a database table, but given the amount of traffic the site has this would produce a very large database very quickly. If any one could give me a pointer or two, that would be great.

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• ImageView source scaling done right. How?

  - by Aleksey Malevaniy

  Scope Image bitmap have to be shown as imageView.setImageBitmap(bitmap) and scaled to fit UI. This could be done via: bitmap = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, true); xml's ImageView attributes such as android:layout_width="newWidth" android:layout_height="newHeight" android:adjustViewBounds="true" android:scaleType="fitCenter" Problem Which way is better for performance? I prefer xml 'cause this is UI specific problem and I prefer to use xmls for UI definition. Also we set width/height values in dp, it means we have the same UI for different screens. Thanks!

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• JAVA. Writing a matrix in a file using column information.

  - by Dmitry

  Hello, everybody! I have a file in which a matrix is stored. This file has a RandomAccessFile type. This matrix is stored by columns. I mean that in an i-th row of this matrix an i-th column (of a real matrix) is stored. There is an example: i-th row: 1 2 3 4 (in the file). That means that the real matrix has an i-th column: (1 2 3 4)(transpose). I need to save this matrix in natural way (by rows) in a new file, which I will then open with FileReader and display with TestArea. DO you know, how to do that? If so, please help =)

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• Why does initWithFrame have the wrong frame value?

  - by greypoint

  I have a subclass of UIButton called INMenuCard and I am overriding the initWithFrame to include an activity indicator. The menuCard places correctly but any internal reference to "frame" give me "inf,inf,0,0" which means my activityIndicator subview is not placed correctly. What might I be missing? @implementation INMenuCard - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { CGRect innerFrame = CGRectInset(frame, 50.0f, 100.0f); activityIndicator = [[UIActivityIndicatorView alloc] initWithFrame:innerFrame]; activityIndicator.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhite; [self addSubview:activityIndicator]; } return self; } I am instantiating INMenuCard with (debugging shows the CGRect values are correct): CGRect cardFrame = CGRectMake(cardX, cardStartY, cardWidth, cardHeight); INMenuCard *menuCard = [[INMenuCard buttonWithType:UIButtonTypeCustom] initWithFrame:cardFrame]; [theView addSubView:menuCard];

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• Multimap Space Issue: Guava

  - by Arpssss

  In my Java code, I am using Guavas Multimap (com.google.common.collect.Multimap) by using this: Multimap< Integer, Integer Index = HashMultimap.create() Here, Multimap key is some portion of URL and value is another portion of URL (converted into integer). Now, I assign my JVM 2560 Mb (2.5 GB) heap space (by using Xmx and Xms). However, it can only store 9 millions of such (key,value) pairs of integers (approx 10 million). But, theoretically (according to memory occupied by int) it should store more. Can anybody help me, 1) Why is this happening (means Multimap is taking lots of space) ? I checked my code with out inserting pairs in Multimap, it takes only 1/2 MB space. 2) Is there any other way or home-baked solution to solve this space issue ? More clearly, how to solve this memory issue ? Thanks in advance and any idea is perfectly OK for me.

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• SVN merge adding parameters. WTF? Or how to do big merges?

  - by HeavyWave

  I am doing an SVN merge for a branch, and in one of the files I see this: GetQueryReferenceData(int sessionId, Int32 sessionId) Which means that the merge tool just added another parameter without asking any questions. Imagine if it was a call to Substring(0) and in another branch it would be Substring(0,2). That is completely different behavior, how does it even get to decide which one to choose? Good thing it came up during compile time. The problem is that it will not be marked as a conflict and will be merged automatically. That is very dangerous behavior and if you don't have the luxury of having a unit test for every line of code - you are screwed. What am I doing wrong and how to do big merges without the merging tool putting in dangerous changes silently? Is there a merge tool that is not language agnostic? I am using Tortoise SVN.

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• How can CopyOnWriteArrayList be thread-safe?

  - by Shooshpanchick

  I've taken a look into OpenJDK's sources of CopyOnWriteArrayList and it seems that all write operations are protected by the same lock and read operations are not protected at all. As I understand, under JMM all accesses to a variable (both read and write) should be protected by lock or reordering effects may occur. For example, set(int, E) method contains these lines (under lock): /* 1 */ int len = elements.length; /* 2 */ Object[] newElements = Arrays.copyOf(elements, len); /* 3 */ newElements[index] = element; /* 4 */ setArray(newElements); The get(int) method, on the other hand, only does return get(getArray(), index);. In my understanding of JMM, this means that get may observe the array in an inconsistent state if statements 1-4 are reordered like 1-2(new)-4-2(copyOf)-3. Do I understand JMM incorrectly or is there any other explanations on why CopyOnWriteArrayList is thread-safe?

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• HTML tag for identifying text

  - by ravi

  I am not very much familiar with HTML programming. If we look at the source code of a page, then we can see what are the HTML tags for which texts and so. It is the case that there is group or class of HTML tags which is used for purpose such that it can be used for main text or so. I mean like '<\input type="radio" name="option"' this tag says that there will a radio button, similar can be make a group of HTML tags such that it consist of text part, which means we look at the tag and not at the content and can say that in between startTag and endTag we have text.

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• Can a MAC address be used as a reliable part of a rights management (DRM) scheme?

  - by Jarrod Mosen

  We're currently writing some software that we want to protect. We thought that registering a user's MAC address in a database upon activation of the software seemed viable; we can profile and grab that with a Java applet, (is there a better way?) so getting it isn't too much of a problem. However, we want their computer to only run the application, and download application files/updates from the server when their MAC address has been verified with their one on-file. We understand that this means a lockdown to one computer, but special changes can be made on request. What would be the best way to verify their MAC address, to see if it exists in the database, and then serve them the files to run the application? (And to simply run it on subsequent requests, to prevent re-downloading.)

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• [java] Threading socket handler for two sided communication in tcp port

  - by raven

  I want to make a chat which will be programed in java. one computer will host the server and the other one will initiate the socket [tcp port]. now from what I read there should be a loop that will constantly read the socket which means it will make the code stuck. I have a button that is 'actionperformed' on mouse release, I want to know if it will work along with the loops that constantly reads the socket so that it will also send the infromation I wrote. If I must thread it, I want to know if the run() method must be void because if I thread it it will mean creating a new class, and the whole GUI is one big class which includes a text area, and it's private. also how can I extract the information from the socket directly to the text area? lets say the textarea variable is called "chatOutput". thx :)

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• Creating tifs directly from VB.Net.

  - by ajl

  The current applications uses .net printdocument to create print jobs which it sends to a standard printer. We use the blackice tif print driver to capture the output and manage it from there. The problem is that some print jobs take 30 seconds to come out of the queue, and blackice will not allow you to change settings on the driver (like output filename) until the job is complete. This means the application has to wait 30 seconds until it can print the next job. Is there a better way? Can I create/print tif images directly from .Net without a 3rd party print driver? Do I risk quality to do this?

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• Java List Sorting: Is there a way to keep a list permantly sorted automatically like TreeMap?

  - by david

  In Java you can build up an ArrayList with items and then call: Collections.sort(list, comparator); Is there anyway to pass in the Comparator at the time of List creation like you can do with TreeMap? The goal is to be able add an element to the list and instead of having it automatically appended to the end of the list, the list would keep itself sorted based on the Comparator and insert the new element at the index determined by the Comparator. So basically the list might have to re-sort upon every new element added. Is there anyway to achieve this in this way with the Comparator or by some other similar means? Thanks.

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• Emulating a transaction-safe SEQUENCE in MySQL

  - by Michael Pliskin

  We're using MySQL with InnoDB storage engine and transactions a lot, and we've run into a problem: we need a nice way to emulate Oracle's SEQUENCEs in MySQL. The requirements are: - concurrency support - transaction safety - max performance (meaning minimizing locks and deadlocks) We don't care if some of the values won't be used, i.e. gaps in sequence are ok. There is an easy way to archieve that by creating a separate InnoDB table with a counter, however this means it will take part in transaction and will introduce locks and waiting. I am thinking to try a MyISAM table with manual locks, any other ideas or best practices?

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• How to modify the Title Bar text for SQL Server Management Studio?

  - by DaveDev

  Sometimes I keep multiple instances of SQL Server Management Studio 2005 open. I might have the dev database open in one, and the production database open in another. These appear in the Windows task bar with the text "Microsoft SQL Serve...", which means it's impossible to differentiate between them unless I open the window and scroll the Object Explorer up to see what server the window is actually connected to. Is ther any way that I can get the window to display the server name first, and then the name of the application? Like "Dev-DB.database_name - Microsoft SQL Serve..." or whatever?

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• An old flaw in X Window System. How does it work?

  - by Legend

  I was going through an article today when it mentioned the following: "We've found many errors over the years. One of the absolute best was the following in the X Window System: if(getuid() != 0 && geteuid == 0) { ErrorF("Only root"); exit(1); } It allowed any local user to get root access. (The tautological check geteuid == 0 was intended to be geteuid() == 0. In its current form, it compress the address of geteuid to 0; given that the function exists, its address is never 0)." The article explained what was wrong with the code but I would like to know what it means to say that "It allowed any local user to get root access". I am not an expert in C but can someone give me an exact context in which this exploit would work? Specifically, what I mean is, lets say I am the local user, how would I get root access if we assume this code to be present somewhere?

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• testing an in app purchase??

  - by hemant

  i developed a application with in app purchases..when user buys the subscription it gets stored on my server..after testing it few times i deleted the data from server to test it again but when i buy it the sandbox environment says u you already purchased this.TAP OK to download it again for free also i have used this test account on my previous application?? does it means i will have to create a new test account for this application?? also by mistake i used this account on apple store..i read somewhere that doing this will make your test account invalid...is it true?? should i create a new account for it??

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• Using a class with const data members in a vector

  - by Max

  Given a class like this: class Foo { const int a; }; Is it possible to put that class in a vector? When I try, my compiler tells me it can't use the default assignment operator. I try to write my own, but googling around tells me that it's impossible to write an assignment operator for a class with const data members. One post I found said that "if you made [the data member] const that means you don't want assignment to happen in the first place." This makes sense. I've written a class with const data members, and I never intended on using assignment on it, but apparently I need assignment to put it in a vector. Is there a way around this that still preserves const-correctness?

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• Any tips of how to handle hierarchial trees in relational model?

  - by George

  Hello all. I have a tree structure that can be n-levels deep, without restriction. That means that each node can have another n nodes. What is the best way to retrieve a tree like that without issuing thousands of queries to the database? I looked at a few other models, like flat table model, Preorder Tree Traversal Algorithm, and so. Do you guys have any tips or suggestions of how to implement a efficient tree model? My objective in the real end is to have one or two queries that would spit the whole tree for me. With enough processing i can display the tree in dot net, but that would be in client machine, so, not much of a big deal. Thanks for the attention

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• Get information about a function in python, looking at source code

  - by Werner

  Hi, the following code comes from the matplotlib gallery: #!/usr/bin/env python from pylab import * x = array([10, 8, 13, 9, 11, 14, 6, 4, 12, 7, 5]) y = array([8.04, 6.95, 7.58, 8.81, 8.33, 9.96, 7.24, 4.26, 10.84, 4.82, 5.68]) I am new to python, and would like to change the content of x and y from an input file. I have two short questions: I could guess what array means, but once I see it on the code, how can I know to which library it belongs and more information about it? Should I use some kind of python debug commands? How do I insert the content of my input file into x? Thanks

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• View / ViewModel - what is the sense (in a WPF control)?

  - by TomTom

  Not as funny as it sounds. Normally the View / ViewModel should decouple the presentation from the business logic. Good. Now, a Control in WPF is basically invisible unless made different (with the exceptions of UserControl and Window that have XAML directly attached). The Style is putting in the "visual presentation" - which basically means a Control does not need a view mechanism as WPF already has one? In addition. the ViewModel is actually part of the Control, or? Just fighting with that stuff. I know in ASP.NET, WinForms the separation makes a lot of sense - but there, basically, controls HAVE an intrinsic look. In WPF, I have some where it makes sense (derived from UserControl), but for the majority of the controls I write, the View & ViewModel look like pretty much totally superflous thanks to the already presenting view mechanism.

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• How can a string timestamp with hours 0 to 24 be parsed

  - by user897052

  I am trying to parse a string timestamp of format "yyyyMMddHHmmss" with DateTime.ParseExact(). The catch is I must allow for an hour value of "24" (i.e. hours can be from 0 to 24; Note: I can't control the input values.) and, of course, that results in an exception. Are there any settings/properties I can set instead of manually parsing/using regex's? If not, any efficient parsing ideas? ex. DateTime.ParseExact("20120911240000", "yyyyMMddHHmmss", System.Globalization.CultureInfo.InvariantCulture); hour 24 means hour 0 of next day (so day + 1, hour = 0)

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• How to find out efficiently the auto-generated id for a new object when using JPA?

  - by webstarg

  Hello, I have an attribute which is annotated with @Id. The ID is going to be generated automatically when persisting the object. That means that the ID-value is not defined before I persist the object. After persisting it, it has an ID (in the database), but unfortunately the field still remains null as long as I don't reload it from the DB. is there any easy way to find out the generated id? Or better: To configure that it will be written into the field? Thanks in advance

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