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Articles indexed Monday April 26 2010

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  • How can I solve NP complete problems in erlang?

    - by Yadira Suazo
    Hi, I already have my operators for, by example, eat banana problem [#op{ action = [climb, on, {object}], preconds = [[at, {place}, {object}], [at, {place}, me], [on, floor, me], [on, floor, {object}], [large, {object}]], add_list = [[on, {object}, me]], del_list = [[on, floor, me]] }, But how can I use it in the function solve(Problem, depth_first, []). And depth_first (Problem, Start) - search_tree(Problem, container.stack, Start).

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  • Silverlight: how to modify the width of ListBox Items in response to user input?

    - by sympatric greg
    I have a simple Silverlight 3 UserControl whose width increases or decreases based on user input. The controls become more wide or more narrow as desired, except for the ListBox items. The ListBox Items grow horizontally to fit their content regardless of HorizontalContentAlignment being set to 'Stretch'. Should I be able to set a property on ListBox.ItemContainerStyle to tell it to widen/narrow with the parent ListBox? There needs to be no horizontal scrolling within this Listbox. Or is there a way to specify the ItemTemplate's StackPanel width that can be modified at runtime? I have bound this to a StaticResource, but do not understand whether I should be able to change the resource value. Can I create and bind to a DependencyProperty of the UserControl itself? I have not determined the syntax of this within the xaml. code: <UserControl x:Class="TheAssembly.GraphicViewer" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:userControls="clr-namespace:TheAssembly" xmlns:core="clr-namespace:System;assembly=mscorlib"> <UserControl.Resources> <userControls:DictionaryAttributeConverter x:Name="MyDictionaryAttributeConverter" /> <core:Double x:Key="ListItemWidth">155</core:Double> </UserControl.Resources> <Grid x:Name="LayoutRoot" Width="175" > <Border Style="{StaticResource DraggableWindowBorder}"> <StackPanel x:Name="RootStackPanel" Orientation="Vertical" HorizontalAlignment="Stretch"> <Border Background="Black" HorizontalAlignment="Stretch" Margin="0"> <TextBlock x:Name="Header" Foreground="White" FontSize="14" TextWrapping="Wrap" Margin="2,0,2,0" Height="25" HorizontalAlignment="Left" Text="{Binding HeaderText}"/> </Border> <TextBlock x:Name="Title" Style="{StaticResource GraphicViewerDetail}" FontSize="12" FontWeight="Medium" TextWrapping="Wrap" Text="{Binding Title}" Margin="3,0,0,0" HorizontalAlignment="Left"/> <ListBox x:Name="AttributeListBox" ItemsSource="{Binding Attributes}" BorderBrush="Red" HorizontalContentAlignment="Stretch" Foreground="AntiqueWhite" Background="Transparent" IsEnabled="False" HorizontalAlignment="Stretch" ScrollViewer.VerticalScrollBarVisibility="Visible" ScrollViewer.HorizontalScrollBarVisibility="Hidden"> <ListBox.ItemContainerStyle> <Style TargetType="ListBoxItem"> <Setter Property="HorizontalAlignment" Value="Stretch"/> <Setter Property="HorizontalContentAlignment" Value="Stretch"/> <Setter Property="Margin" Value="0,-2,0,0"/> </Style> </ListBox.ItemContainerStyle> <ListBox.ItemTemplate> <DataTemplate> <StackPanel x:Name="ListBoxItemStackPanel" HorizontalAlignment="Stretch" Orientation="Vertical" > <TextBlock FontSize="10" Text="{Binding Key}" Foreground="White" FontWeight="Bold" HorizontalAlignment="Stretch" Margin="2,0,0,0" TextWrapping="Wrap"/> <TextBlock FontSize="10" Text="{Binding Value}" Foreground="White" Margin="6,-2,0,0" TextWrapping="Wrap" HorizontalAlignment="Stretch" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </StackPanel> </Border> </Grid>

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  • ASP .NET 2.0 C# AjaxPro RegisterTypeForAjax

    - by Dan7el
    I am wondering if RegisterTypeForAjax isn't working correctly. I am getting the error noted at the end of the code block below. Sample is from here: http://www.ajaxtutorials.com/asp-net-ajax-quickstart/tutorial-introduction-to-ajax-in-asp-net-2-0-and-c/ Any ideas as to why I'm getting this error? Thanks. ASP .NET 2.0 C# Here is the code-behind: using System; using System.Data; using System.Data.SqlClient; using System.Configuration; using System.Collections; using System.Collections.Generic; using System.Web; using System.Web.Security; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.WebControls.WebParts; using System.Web.UI.HtmlControls; using AjaxPro; namespace WebApplication1 { public partial class Ajax_CSharp : System.Web.UI.Page { protected override void OnInit( EventArgs e ) { base.OnInit( e ); Load += new EventHandler( Page_Load ); } protected void Page_Load( object sender, EventArgs e ) { Utility.RegisterTypeForAjax( typeof( Ajax_CSharp ) ); } [ AjaxMethod( HttpSessionStateRequirement.ReadWrite ) ] public string GetData() { // method gets a row from the db and returns a string. } } Here is the ASPX page: <%@ Page Language="C#" AutoEventWireup="false" CodeBehind="Default.aspx.cs" Inherits="WebApplication1.Ajax_CSharp" % Untitled Page function GetData() { var response; Ajax_CSharp.GetData( GetData_CallBack ); } function GetData_CallBack( response ) { var response = response.value; if ( response == "Empty" ) { alert( "No Record Found." ); } else if ( response == "Error" ) { alert( "An Error Occurred in Accessing the Database !!!" ); } else { var arr = response.split( "~" ); var empID = arr[0].split( "," ); var empName = arr[1].split( "," ); document.getElementById( 'dlistEmployee' ).length = 0; for ( var i = 0; i < empID.Length; i++ ) { var o = document.createElement( "option" ); o.value = empID[i]; o.text = empName[i]; document.getElementById( 'dlistEmployee' ).add( o ); } } } function dodisplay() { var selIndex = document.getElementById( "dlistEmployee" ).selectedIndex; var empName = document.getElementById( "dlistEmployee" ).options( selIndex ).text; var empID = document.getElementById( "dlistEmployee" ).options( selIndex ).value; document.getElementById( "lblResult" ).innerHTML = "You have selected " + empName + " (ID: " + empID + " )"; } </script>    Run it and click on the button and I get this error: Webpage error details User Agent: Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.4506.2152; .NET CLR 3.5.30729; InfoPath.2; MS-RTC LM 8) Timestamp: Mon, 26 Apr 2010 17:22:44 UTC Message: 'Ajax_CSharp' is undefined Line: 13 Char: 11 Code: 0 URI: http://localhost:4678/Default.aspx

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  • Selecting item from set given distribution

    - by JH
    I have a set of X items such as {blower, mower, stove} and each item has a certain percentage of times it should be selected from the overall set {blower=25%,mower=25%,stove=75%} along with a certain distribution that these items should follow (blower should be selected more at the beginning of selection and stove more at the end). We are given a number of objects to be overall selected (ie 100) and a overall time to do this in (say 100 seconds). I was thinking of using a roulette wheel algorithm where the weights on the wheel are affected by the current distribution as a function of the elapsed time (and the allowed duration) so that simple functions could be used to determine the weight. Are there any common approaches to problems like this that anyone is aware of? Currently i have programmed something similar to this in java using functions such as x^2 (with correct normalization for the weights) to ensure that a good distribution occurs. Other suggestions or common practices would be welcome :-)

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  • Java Container constraints question

    - by llm
    I am using the following: java.awt.Container.add(Component comp, Object constraints) How do I specificy the constraints object? I need to be able to place a component within the container. Oh and my class extends JInternalFrame if this helps... I need to specify coordinates to place the component within the container

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  • Google App Engine JDO error caused by GregorianCalendar ?

    - by Frank
    My class looks like this : import javax.jdo.annotations.IdGeneratorStrategy; import javax.jdo.annotations.IdentityType; import javax.jdo.annotations.PersistenceCapable; import javax.jdo.annotations.Persistent; import javax.jdo.annotations.PrimaryKey; @PersistenceCapable(identityType=IdentityType.APPLICATION) public class Contact_Info implements Serializable { @PrimaryKey @Persistent(valueStrategy=IdGeneratorStrategy.IDENTITY) Long Id; public static final long serialVersionUID=26362862L; @Persistent String Contact_Id=""; @Persistent GregorianCalendar Date_1; public Contact_Info() { } public void setId(Long value) { Id=value; } public Long getId() { return Id; } public void setContact_Id(String value) { Contact_Id=value; } public String getContact_Id() { return Contact_Id; } public void setDate_1(GregorianCalendar value) { Date_1=value; } public GregorianCalendar getDate_1() { return Date_1; } public String toString() { return Contact_Id; } } When it's run, I got the following error : java.lang.UnsupportedOperationException org.datanucleus.store.appengine.EntityUtils.getPropertyName(EntityUtils.java:62) org.datanucleus.store.appengine.DatastoreFieldManager.storeObjectField(DatastoreFieldManager.java:839) org.datanucleus.state.AbstractStateManager.providedObjectField(AbstractStateManager.java:1037) PayPal_Monitor.Contact_Info.jdoProvideField(Contact_Info.java) PayPal_Monitor.Contact_Info.jdoProvideFields(Contact_Info.java) org.datanucleus.state.JDOStateManagerImpl.provideFields(JDOStateManagerImpl.java:2715) org.datanucleus.store.appengine.DatastorePersistenceHandler.insertPreProcess(DatastorePersistenceHandler.java:341) org.datanucleus.store.appengine.DatastorePersistenceHandler.insertObjects(DatastorePersistenceHandler.java:251) If I take out the "GregorianCalendar Date_1", it works correctly, what should I do to fix it ? I do need the date in it. Frank

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  • Secure php code for copyright

    - by cosy
    I have an eCommerce platform, and i wand to secure it. How can it be possible ? I don't want to somebody copy my code. Like a license for 1 year with a code for activation. Or somethings like this. Sorry my English, thanks a lot!

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  • What is this CSS rule?

    - by Lisa
    In the son of suckerfish drop down menu: http://www.htmldog.com/articles/suckerfish/dropdowns/example/ You see this rule w\idth: 13.9em; This can't be a typo as it appears various times in the css. What is it for?

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  • Is it getting to be time for C# to support compile-time macros?

    - by Robert Rossney
    Thus far, Microsoft's C# team has resisted adding formal compile-time macro capabilities to the language. There are aspects of programming with WPF that seem (to me, at least) to be creating some compelling use cases for macros. Dependency properties, for instance. It would be so nice to just be able to do something like this: [DependencyProperty] public string Foo { get; set; } and have the body of the Foo property and the static FooProperty property be generated automatically at compile time. Or, for another example an attribute like this: [NotifyPropertyChanged] public string Foo { get; set; } that would make the currently-nonexistent preprocessor produce this: private string _Foo; public string Foo { get { return _Foo; } set { _Foo = value; OnPropertyChanged("Foo"); } } You can implement change notification with PostSharp, and really, maybe PostSharp is a better answer to the question. I really don't know. Assuming that you've thought about this more than I have, which if you've thought about it at all you probably have, what do you think? (This is clearly a community wiki question and I've marked it accordingly.)

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  • Exception on malloc for a structure in C

    - by Derek
    Hi all, I have a structure defined like so: typedef struct { int n; int *n_p; void **list_pp; size_t rec_size; int n_buffs; size_t buff_size } fl_hdr_type; and in my code I Have a function for initlialization that has the following fl_hdr_type *fl_hdr; fl_hdr = malloc(sizeof(fl_hdr_type) + (buff_size_n * rec_size_n)); where those buffer size are passed in to the function to allow space for the buffers as well. The size is pretty small typically..100*50 or something like that..plenty of memory on this system to allocate it. Any ideas why this fails?

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  • Spring Security and the Synchronizer Token J2EE pattern, problem when authentication fails.

    - by dfuse
    Hey, we are using Spring Security 2.0.4. We have a TransactionTokenBean which generates a unique token each POST, the bean is session scoped. The token is used for the duplicate form submission problem (and security). The TransactionTokenBean is called from a Servlet filter. Our problem is the following, after a session timeout occured, when you do a POST in the application Spring Security redirects to the logon page, saving the original request. After logging on again the TransactionTokenBean is created again, since it is session scoped, but then Spring forwards to the originally accessed url, also sending the token that was generated at that time. Since the TransactionTokenBean is created again, the tokens do not match and our filter throws an Exception. I don't quite know how to handle this elegantly, (or for that matter, I can't even fix it with a hack), any ideas? This is the code of the TransactionTokenBean: public class TransactionTokenBean implements Serializable { public static final int TOKEN_LENGTH = 8; private RandomizerBean randomizer; private transient Logger logger; private String expectedToken; public String getUniqueToken() { return expectedToken; } public void init() { resetUniqueToken(); } public final void verifyAndResetUniqueToken(String actualToken) { verifyUniqueToken(actualToken); resetUniqueToken(); } public void resetUniqueToken() { expectedToken = randomizer.getRandomString(TOKEN_LENGTH, RandomizerBean.ALPHANUMERICS); getLogger().debug("reset token to: " + expectedToken); } public void verifyUniqueToken(String actualToken) { if (getLogger().isDebugEnabled()) { getLogger().debug("verifying token. expected=" + expectedToken + ", actual=" + actualToken); } if (expectedToken == null || actualToken == null || !isValidToken(actualToken)) { throw new IllegalArgumentException("missing or invalid transaction token"); } if (!expectedToken.equals(actualToken)) { throw new InvalidTokenException(); } } private boolean isValidToken(String actualToken) { return StringUtils.isAlphanumeric(actualToken); } public void setRandomizer(RandomizerBean randomizer) { this.randomizer = randomizer; } private Logger getLogger() { if (logger == null) { logger = Logger.getLogger(TransactionTokenBean.class); } return logger; } } and this is the Servlet filter (ignore the Ajax stuff): public class SecurityFilter implements Filter { static final String AJAX_TOKEN_PARAM = "ATXTOKEN"; static final String TOKEN_PARAM = "TXTOKEN"; private WebApplicationContext webApplicationContext; private Logger logger = Logger.getLogger(SecurityFilter.class); public void init(FilterConfig config) { setWebApplicationContext(WebApplicationContextUtils.getWebApplicationContext(config.getServletContext())); } public void destroy() { } public void doFilter(ServletRequest req, ServletResponse response, FilterChain chain) throws IOException, ServletException { HttpServletRequest request = (HttpServletRequest) req; if (isPostRequest(request)) { if (isAjaxRequest(request)) { log("verifying token for AJAX request " + request.getRequestURI()); getTransactionTokenBean(true).verifyUniqueToken(request.getParameter(AJAX_TOKEN_PARAM)); } else { log("verifying and resetting token for non-AJAX request " + request.getRequestURI()); getTransactionTokenBean(false).verifyAndResetUniqueToken(request.getParameter(TOKEN_PARAM)); } } chain.doFilter(request, response); } private void log(String line) { if (logger.isDebugEnabled()) { logger.debug(line); } } private boolean isPostRequest(HttpServletRequest request) { return "POST".equals(request.getMethod().toUpperCase()); } private boolean isAjaxRequest(HttpServletRequest request) { return request.getParameter("AJAXREQUEST") != null; } private TransactionTokenBean getTransactionTokenBean(boolean ajax) { return (TransactionTokenBean) webApplicationContext.getBean(ajax ? "ajaxTransactionTokenBean" : "transactionTokenBean"); } void setWebApplicationContext(WebApplicationContext context) { this.webApplicationContext = context; } }

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  • Lockless queue implementation ends up having a loop under stress

    - by Fozi
    I have lockless queues written in C in form of a linked list that contains requests from several threads posted to and handled in a single thread. After a few hours of stress I end up having the last request's next pointer pointing to itself, which creates an endless loop and locks up the handling thread. The application runs (and fails) on both Linux and Windows. I'm debugging on Windows, where my COMPARE_EXCHANGE_PTR maps to InterlockedCompareExchangePointer. This is the code that pushes a request to the head of the list, and is called from several threads: void push_request(struct request * volatile * root, struct request * request) { assert(request); do { request->next = *root; } while(COMPARE_EXCHANGE_PTR(root, request, request->next) != request->next); } This is the code that gets a request from the end of the list, and is only called by a single thread that is handling them: struct request * pop_request(struct request * volatile * root) { struct request * volatile * p; struct request * request; do { p = root; while(*p && (*p)->next) p = &(*p)->next; // <- loops here request = *p; } while(COMPARE_EXCHANGE_PTR(p, NULL, request) != request); assert(request->next == NULL); return request; } Note that I'm not using a tail pointer because I wanted to avoid the complication of having to deal with the tail pointer in push_request. However I suspect that the problem might be in the way I find the end of the list. There are several places that push a request into the queue, but they all look generaly like this: // device->requests is defined as struct request * volatile requests; struct request * request = malloc(sizeof(struct request)); if(request) { // fill out request fields push_request(&device->requests, request); sem_post(device->request_sem); } The code that handles the request is doing more than that, but in essence does this in a loop: if(sem_wait_timeout(device->request_sem, timeout) == sem_success) { struct request * request = pop_request(&device->requests); // handle request free(request); } I also just added a function that is checking the list for duplicates before and after each operation, but I'm afraid that this check will change the timing so that I will never encounter the point where it fails. (I'm waiting for it to break as I'm writing this.) When I break the hanging program the handler thread loops in pop_request at the marked position. I have a valid list of one or more requests and the last one's next pointer points to itself. The request queues are usually short, I've never seen more then 10, and only 1 and 3 the two times I could take a look at this failure in the debugger. I thought this through as much as I could and I came to the conclusion that I should never be able to end up with a loop in my list unless I push the same request twice. I'm quite sure that this never happens. I'm also fairly sure (although not completely) that it's not the ABA problem. I know that I might pop more than one request at the same time, but I believe this is irrelevant here, and I've never seen it happening. (I'll fix this as well) I thought long and hard about how I can break my function, but I don't see a way to end up with a loop. So the question is: Can someone see a way how this can break? Can someone prove that this can not? Eventually I will solve this (maybe by using a tail pointer or some other solution - locking would be a problem because the threads that post should not be locked, I do have a RW lock at hand though) but I would like to make sure that changing the list actually solves my problem (as opposed to makes it just less likely because of different timing).

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  • LLBL Gen Predicate Filter

    - by Neil
    I am new to LLBLGen Pro and am checking for duplicate, I have the following SQL: SQL: select a.TopicId,atc.TopicCategoryId,a.Headline from article a inner join ArticleTopicCategory atc on atc.ArticleId = a.Id where a.TopicId = 'C0064FAE-093B-466E-8745-230534867D2F' and a.Headline = 'Test' and atc.TopicCategoryId in ('004D64F7-474C-48F9-9887-17B1E7532A84') Whenever I step though my function, it always returns 0: LLBLGen Code: public bool CheckDuplicateArticle(Guid topicId, List<Guid> categories, string headline) { ArticleCollection articles = new ArticleCollection(); PredicateExpression filter = new PredicateExpression(); RelationCollection relation = new RelationCollection(); relation.Add(ArticleEntity.Relations.ArticleTopicCategoryEntityUsingArticleId); filter.AddWithAnd(ArticleFields.TopicId == topicId); filter.AddWithAnd(ArticleTopicCategoryFields.Id == categories); filter.AddWithAnd(ArticleFields.Headline == headline); articles.GetMulti(filter, 0, null, relation); return articles.Count > 0; } Any help would be appreciated!

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  • I have found an inheritance.

    <b>Technology & Life Integration:</b> "You may not know me as I received your attention from a browser link. This is very important so please continue reading. This letter has the possibility of changing your life. With your help we can realise that dream."

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  • Does such beast exist

    - by ggonsalv
    I know of whoami.exe. Is there a version called whereami.exe The output should be able to tell me if I am on a LAN, wireless or VPN. the machines would be running Windows Xp or better.

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  • In SSRS 2000 dynamicly setting the datasource

    - by Christopher Kelly
    Is there a way in SSRS 2000 to set the datasource that a report is using via the webservice? I am currently generating reports using the SSRS2000_ReportService.ReportingService webservice and want to dyanmicclyswitch between a couple of shared data sources on demand. I am using C# but could adapt other languages if needed.

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  • Hard Drives: Always on or spin up/down as needed?

    - by Terminal Frost
    The specific application is a NAS that hosts media content and is frequently accessed during the day. My NAS was probably cycling on and off around 5 times a day so I decided to not allow it to spin down. I'm thinking this will be better for the drive, but I am not sure. I am wondering, however, if there is any concrete information out there as to what causes more detrimental wear on a hard disk: Spinning 24/7 or cycling on and off as needed?

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  • How to send SMS Using SMS Email Gateway internationally?

    - by user35259
    Hi All, I don't know if this is the right place to post my question but, anyways, i will just ask. I'm trying to send SMS messages from a unix-based machine by sending a mail to [email protected]. This works very fine and messages are received normally. What I want to ask about is, am I able to use this service to send SMS messages to an international number? What about the country code? How will I add it and the format needs ten digits only? Thanks

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  • How to Become an SEO Expert

    Do you have a website, a quality product but need targeted traffic. Search engine optimization is the foundation of getting organic traffic to any site or blog. Today were going to discuss several simple yet powerful ways of making your site SEO friendly and getting you that targeted traffic you need.

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  • Building Dynamic Websites With XML, XSLT, and ASP

    While online businesses are expanding rapidly in this day and age and searching for a way to reduce website cost, it is imperative for the internet business executive to understand and utilize the technical tools available on the internet to build a dynamic website. XML, XSLT, and ASP are internet website building tools that operate effectively to help sites survive in the booming online business market as well as reduce website cost.

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  • The Cobra Programming Language

    There are suddenly a number of strong alternatives to C# or VB. F#, IronPython and Iron Ruby are now joined by an open-source alternative called Cobra. Phil is taken by surprise at a language that is so intuitive to use that it is almost like pseudocode.

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  • Wait set time for user input C# console app

    - by Marlon
    For a Console app, I need to know how to wait at set amount of time (about 10 seconds), for a user to input a key or set of keys, before proceeding with an 'auto run' portion of the application. This is bugging me because I can't quite figure out how the timer works, or threading.sleep, what should I use? Been googling all day.

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