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  • Polymorphism, Autoboxing, and Implicit Conversions

    - by dbyrne
    Would you consider autoboxing in Java to be a form of polymorphism? Put another way, do you think autoboxing extends the polymorphic capabilities of Java? What about implicit conversions in Scala? My opinion is that they are both examples of polymorphism. Both features allow values of different data types to be handled in a uniform manner. My colleague disagrees with me. Who is right?

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  • Is factory method proper design for my problem?

    - by metdos
    Hello Everyone, here is my problem and I'm considering to use factory method in C++, what are your opinions ? There are a Base Class and a lot of Subclasses. I need to transfer objects on network via TCP. I will create objects in first side, and using this object I will create a byte array TCP message, and send it to other side. On the other side I will decompose TCP message, I will create object and I will add this object to a polymorphic queue.

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  • Entity Framework Polymorphism

    - by Chubbs
    Hey guys, I wanted some help with trying to implement a simple polymorphic relationship using Entity Framework. An example of a relationship I would like to implement: Comment table ItemType ('Video', 'User') ItemID Body Video has many Comments User has many Comments No idea the best way to do this, I come from a Ruby on Rails way of thinking.

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  • GHC.Generics and Type Families

    - by jberryman
    This is a question related to my module here, and is simplified a bit. It's also related to this previous question, in which I oversimplified my problem and didn't get the answer I was looking for. I hope this isn't too specific, and please change the title if you can think if a better one. Background My module uses a concurrent chan, split into a read side and write side. I use a special class with an associated type synonym to support polymorphic channel "joins": {-# LANGUAGE TypeFamilies #-} class Sources s where type Joined s newJoinedChan :: IO (s, Messages (Joined s)) -- NOT EXPORTED --output and input sides of channel: data Messages a -- NOT EXPORTED data Mailbox a instance Sources (Mailbox a) where type Joined (Mailbox a) = a newJoinedChan = undefined instance (Sources a, Sources b)=> Sources (a,b) where type Joined (a,b) = (Joined a, Joined b) newJoinedChan = undefined -- and so on for tuples of 3,4,5... The code above allows us to do this kind of thing: example = do (mb , msgsA) <- newJoinedChan ((mb1, mb2), msgsB) <- newJoinedChan --say that: msgsA, msgsB :: Messages (Int,Int) --and: mb :: Mailbox (Int,Int) -- mb1,mb2 :: Mailbox Int We have a recursive action called a Behavior that we can run on the messages we pull out of the "read" end of the channel: newtype Behavior a = Behavior (a -> IO (Behavior a)) runBehaviorOn :: Behavior a -> Messages a -> IO () -- NOT EXPORTED This would allow us to run a Behavior (Int,Int) on either of msgsA or msgsB, where in the second case both Ints in the tuple it receives actually came through separate Mailboxes. This is all tied together for the user in the exposed spawn function spawn :: (Sources s) => Behavior (Joined s) -> IO s ...which calls newJoinedChan and runBehaviorOn, and returns the input Sources. What I'd like to do I'd like users to be able to create a Behavior of arbitrary product type (not just tuples) , so for instance we could run a Behavior (Pair Int Int) on the example Messages above. I'd like to do this with GHC.Generics while still having a polymorphic Sources, but can't manage to make it work. spawn :: (Sources s, Generic (Joined s), Rep (Joined s) ~ ??) => Behavior (Joined s) -> IO s The parts of the above example that are actually exposed in the API are the fst of the newJoinedChan action, and Behaviors, so an acceptable solution can modify one or all of runBehaviorOn or the snd of newJoinedChan. I'll also be extending the API above to support sums (not implemented yet) like Behavior (Either a b) so I hoped GHC.Generics would work for me. Questions Is there a way I can extend the API above to support arbitrary Generic a=> Behavior a? If not using GHC's Generics, are there other ways I can get the API I want with minimal end-user pain (i.e. they just have to add a deriving clause to their type)?

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  • C++ game designing & polymorphism question

    - by Kotti
    Hi! I'm trying to implement some sort of 'just-for-me' game engine and the problem's plot goes the following way: Suppose I have some abstract interface for a renderable entity, e.g. IRenderable. And it's declared the following way: interface IRenderable { // (...) // Suppose that Backend is some abstract backend used // for rendering, and it's implementation is not important virtual void Render(Backend& backend) = 0; }; What I'm doing right now is something like declaring different classes like class Ball : public IRenderable { virtual void Render(Backend& backend) { // Rendering implementation, that is specific for // the Ball object // (...) } }; And then everything looks fine. I can easily do something like std::vector<IRenderable*> items, push some items like new Ball() in this vector and then make a call similiar to foreach (IRenderable* in items) { item->Render(backend); } Ok, I guess it is the 'polymorphic' way, but what if I want to have different types of objects in my game and an ability to manipulate their state, where every object can be manipulated via it's own interface? I could do something like struct GameState { Ball ball; Bonus bonus; // (...) }; and then easily change objects state via their own methods, like ball.Move(...) or bonus.Activate(...), where Move(...) is specific for only Ball and Activate(...) - for only Bonus instances. But in this case I lose the opportunity to write foreach IRenderable* simply because I store these balls and bonuses as instances of their derived, not base classes. And in this case the rendering procedure turns into a mess like ball.Render(backend); bonus.Render(backend); // (...) and it is bad because we actually lose our polymorphism this way (no actual need for making Render function virtual, etc. The other approach means invoking downcasting via dynamic_cast or something with typeid to determine the type of object you want to manipulate and this looks even worse to me and this also breaks this 'polymorphic' idea. So, my question is - is there some kind of (probably) alternative approach to what I want to do or can my current pattern be somehow modified so that I would actually store IRenderable* for my game objects (so that I can invoke virtual Render method on each of them) while preserving the ability to easily change the state of these objects? Maybe I'm doing something absolutely wrong from the beginning, if so, please point it out :) Thanks in advance!

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  • Haskell: list of elements with class restriction

    - by user1760586
    here's my question: this works perfectly: type Asdf = [Integer] type ListOfAsdf = [Asdf] Now I want to do the same but with the Integral class restriction: type Asdf2 a = (Integral a) => [a] type ListOfAsdf2 = (Integral a) => [Asdf2 a] I got this error: Illegal polymorphic or qualified type: Asdf2 a Perhaps you intended to use -XImpredicativeTypes In the type synonym declaration for `ListOfAsdf2' I have tried a lot of things but I am still not able to create a type with a class restriction as described above. Thanks in advance!!! =) Dak

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  • Are there any data-binding solution that works in C++ and GWT and supports structures polymorphism?

    - by user116854
    I expect it should share a common description, like XmlSchema or IDL and should generate classes for target language. I found Thrift and it's really nice solution, but it doesn't support structures polymorphism. I would like to have collections of base class objects, where I could place instances of subclasses, serialize this and deserialize at the opposite side. Some mechanism of polymorphic behavior support, like Visitor, would be a perfect. Does anybody know something suitable for these requirements?

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  • How can I view the source code for a particular `predict` function?

    - by merlin2011
    Based on the documentation, predict is a polymorphic function in R and a different function is actually called depending on what is passed as the first argument. However, the documentation does not give any information about the names of the functions that predict actually invokes for any particular class. Normally, one could type the name of a function to get its source, but this does not work with predict. If I want to view the source code for the predict function when invoked on objects of the type glmnet, what is the easiest way?

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  • How to handle business rules with a REST API?

    - by Ciprio
    I have a REST API to manage a booking system I'm searching how to manage this situation : A customer can book a time slot : A TimeSlot resource is created and linked to a Person resource. In order to create the link between a time lot and a person, the REST client send a POST request on the TimeSlot resource But if too many people booked the same slot (let's say the limit is 5 links), it must be impossible to create more associations. How can I handle this business restriction ? Can I return a 404 status code with a JSON response detailing the error with a status code ? Is it a RESTFul approach ? EDIT : Like suggested below I used status 409 Conflict in addition to a JSON response detailing the error

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  • 3 tier architecture in objective-c

    - by hba
    I just finished reading the objective-c developer handbook from apple. So I pretty much know everything that there is to know about objective-c (hee hee hee). I was wondering how do I go about designing a 3-tier application in objective-c. The 3-tiers being a front-end application in Cocoa, a middle-tier in pure objective-c and a back-end (data access also in objective-c and mysql db). I'm not really interested in discussing why I'd need a 3-tier architecture, I'd like to narrow the discussion to the 'how'. For example, can I have 3 separate x-code projects one for each tier? If so how would I link the projects together. In java, I can export each tier as a jar file and form the proper associations.

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  • Types of ER Diagrams

    - by syrion
    I'm currently taking a class for database design, and we're using the ER diagram style designed by Peter Chen. I have a couple of problems with this style: Keys in relationships don't seem realistic. In practice, synthetic keys like "orderid" seem to be used in almost all tables, including association tables, but the Chen style diagrams heavily favor (table1key, table2key) compound keys. There is no notation for datatype. The diamond shape for associations is horrible, and produces a cluttered diagram. In general, it just seems hard to capture some relationships with the Chen system. What ERD style, if any, do you use? What has been the most popular in your workplaces? What tools have you used, or do you use, to create these diagrams?

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  • google-chrome video application association

    - by Ben Lee
    Is there any way to tell google-chrome to launch video files of particular types in an external application (or even just to bring up the download box as if the type was un-handled), instead of showing the video inside the browser? Searching online, it seems that chrome is supposed to use xdg-mime for file associations, but apparently is ignoring this for video. For example, when I do: xdg-mime query default video/mpeg It returns dragonplayer.desktop. But when I click on a mpeg video link, chrome displays it internally instead of launching Dragon Player (if I double click on a mpeg file in my file manager, on the other hand, it does open Dragon Player). So is there a way to tell chrome to respect this setting, or another way to coax chrome into opening the file externally? If it matters, I'm running the latest version of google-chrome stable (not chromium) at the time of writing, v. 18.0.1025.151, on kubuntu 11.10.

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  • Models, controllers, and code reuse

    - by user11715
    I have a blog where users can post comments. When creating a comment, various things happen: creating the comment object, associations, persisting sending notification emails to post's author given his preferences sending notification to moderators given their preferences updating a fulltext database for search ... I could put all this in the controller, but what if I want to reuse this code ? e.g. I would like to provide an API for posting comments. I could also put this in the model, but I wonder if I won't lose flexibility by doing so. And would it be acceptable to do all of this from the model layer ? What would you do ?

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  • WebCenter Customer Spotlight: spectrumK Holding GmbH

    - by me
    Solution Summary spectrumK Holding GmbH was founded in 2007 by various German health insurance funds and national insurance associations and is a service provider for the healthcare market, covering patient care management, financial management, and information management, as well as payment services and legal counseling. spectrumK Holding GmbH business objectives was to implement innovative new Web-based services and solution systems for health insurance funds by integrating a multitude of isolated solutions from different organizations. Using Oracle WebCenter Portal, Oracle WebCenter Content, and Site Studio, the customer created a multiple-portal environment and deployed the 1st three applications for patient receipt, a medication navigator, and disability information. spectrumK Holding GmbH accelerated time-to-market for new features by reducing the development time, achieved 40% development and cost savings using standard modules and realized 80% overall savings using the Oracle multiple portal environment, as compared to individual installations. >> Read the full story

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  • Professional Development – Difference Between Bio, CV and Resume

    - by Pinal Dave
    Applying for work can be very stressful – you want to put your best foot forward, and it can be very hard to sell yourself to a potential employer while highlighting your best characteristics and answering questions.  On top of that, some jobs require different application materials – a biography (or bio), a curriculum vitae (or CV), or a resume.  These things seem so interchangeable, so what is the difference? Let’s start with the one most of us have heard of – the resume.  A resume is a summary of your job and education history.  If you have ever applied for a job, you will have used a resume.  The ability to write a good resume that highlights your best characteristics and emphasizes your qualifications for a specific job is a skill that will take you a long way in the world.  For such an essential skill, unfortunately it is one that many people struggle with. RESUME So let’s discuss what makes a great resume.  First, make sure that your name and contact information are at the top, in large print (slightly larger font than the rest of the text, size 14 or 16 if the rest is size 12, for example).  You need to make sure that if you catch the recruiter’s attention and they know how to get a hold of you. As for qualifications, be quick and to the point.  Make your job title and the company the headline, and include your skills, accomplishments, and qualifications as bullet points.  Use good action verbs, like “finished,” “arranged,” “solved,” and “completed.”  Include hard numbers – don’t just say you “changed the filing system,” say that you “revolutionized the storage of over 250 files in less than five days.”  Doesn’t that sentence sound much more powerful? Curriculum Vitae (CV) Now let’s talk about curriculum vitae, or “CVs”.  A CV is more like an expanded resume.  The same rules are still true: put your name front and center, keep your contact info up to date, and summarize your skills with bullet points.  However, CVs are often required in more technical fields – like science, engineering, and computer science.  This means that you need to really highlight your education and technical skills. Difference between Resume and CV Resumes are expected to be one or two pages long – CVs can be as many pages as necessary.  If you are one of those people lucky enough to feel limited by the size constraint of resumes, a CV is for you!  On a CV you can expand on your projects, highlight really exciting accomplishments, and include more educational experience – including GPA and test scores from the GRE or MCAT (as applicable).  You can also include awards, associations, teaching and research experience, and certifications.  A CV is a place to really expand on all your experience and how great you will be in this particular position. Biography (Bio) Chances are, you already know what a bio is, and you have even read a few of them.  Think about the one or two paragraphs that every author includes in the back flap of a book.  Think about the sentences under a blogger’s photo on every “About Me” page.  That is a bio.  It is a way to quickly highlight your life experiences.  It is essentially the way you would introduce yourself at a party. Where a bio is required for a job, chances are they won’t want to know about where you were born and how many pets you have, though.  This is a way to summarize your entire job history in quick-to-read format – and sometimes during a job hunt, being able to get to the point and grab the recruiter’s interest is the best way to get your foot in the door.  Think of a bio as your entire resume put into words. Most bios have a standard format.  In paragraph one, talk about your most recent position and accomplishments there, specifically how they relate to the job you are applying for.  If you have teaching or research experience, training experience, certifications, or management experience, talk about them in paragraph two.  Paragraph three and four are for highlighting publications, education, certifications, associations, etc.  To wrap up your bio, provide your contact info and availability (dates and times). Where to use What? For most positions, you will know exactly what kind of application to use, because the job announcement will state what materials are needed – resume, CV, bio, cover letter, skill set, etc.  If there is any confusion, choose whatever the industry standard is (CV for technical fields, resume for everything else) or choose which of your documents is the strongest. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, PostADay, Professional Development, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • How to decide whether to implement an operation as Entity operation vs Service operation in Domain Driven Design?

    - by Louis Rhys
    I am reading Evans's Domain Driven Design. The book says that there are entity and there are services. If I were to implement an operation, how to decide whether I should add it as a method on an entity or do it in a service class? e.g. myEntity.DoStuff() or myService.DoStuffOn(myEntity)? Does it depend on whether other entities are involved? If it involves other entities, implement as service operation? But entities can have associations and can traverse it from there too right? Does it depend on stateless or not? But service can also access entities' variable, right? Like in do stuff myService.DoStuffOn, it can have code like if(myEntity.IsX) doSomething(); Which means that it will depend on the state? Or does it depend on complexity? How do you define complex operations?

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  • NHibernate Pitfalls: Lazy Scalar Properties Must Be Auto

    - by Ricardo Peres
    This is part of a series of posts about NHibernate Pitfalls. See the entire collection here. NHibernate supports lazy properties not just for associations (many to one, one to one, one to many, many to many) but also for scalar properties. This allows, for example, only loading a potentially large BLOB or CLOB from the database if and when it is necessary, that is, when the property is actually accessed. In order for this to work, other than having to be declared virtual, the property can’t have an explicitly declared backing field, it must be an auto property: 1: public virtual String MyLongTextProperty 2: { 3: get; 4: set; 5: } 6:  7: public virtual Byte [] MyLongPictureProperty 8: { 9: get; 10: set; 11: } All lazy scalar properties are retrieved at the same time, when one of them is accessed.

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  • L'Allemagne appelle à boycotter Facebook, suite aux modifications de la politique de confidentialité

    Mise à jour du 09.04.2010 par Katleen L'Allemagne appelle à boycotter Facebook, suite aux modifications de la politique de confidentialité du site Suite à la nouvelle politique du site communautaire en matière de gestion de la vie privée (voir article précédent, ci-dessous), l'Allemagne part en croisade. Mardi, la ministre allemande de la Consommation a adressé une lettre ouvert à Mark Zuckerberg, le fondateur de Facebook. Elle y remet en cause la récente modifications des paramètres de confidentialité du réseau social. Mercredi, c'est la Fédération des organisations de consommateurs allemands (VZBZ), forte de 42 associations de défense de ses citoyens, qui a lancé un appel aux ...

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  • ADF Reusable Artefacts

    - by Arda Eralp
    Primary reusable ADF Business Component: Entity Objects (EOs) View Objects (VOs) Application Modules (AMs) Framework Extensions Classes Primary reusable ADF Controller: Bounded Task Flows (BTFs) Task Flow Templates Primary reusable ADF Faces: Page Templates Skins Declarative Components Utility Classes Certain components will often be used more than once. Whether the reuse happens within the same application, or across different applications, it is often advantageous to package these reusable components into a library that can be shared between different developers, across different teams, and even across departments within an organization. In the world of Java object-oriented programming, reusing classes and objects is just standard procedure. With the introduction of the model-view-controller (MVC) architecture, applications can be further modularized into separate model, view, and controller layers. By separating the data (model and business services layers) from the presentation (view and controller layers), you ensure that changes to any one layer do not affect the integrity of the other layers. You can change business logic without having to change the UI, or redesign the web pages or front end without having to recode domain logic. Oracle ADF and JDeveloper support the MVC design pattern. When you create an application in JDeveloper, you can choose many application templates that automatically set up data model and user interface projects. Because the different MVC layers are decoupled from each other, development can proceed on different projects in parallel and with a certain amount of independence. ADF Library further extends this modularity of design by providing a convenient and practical way to create, deploy, and reuse high-level components. When you first design your application, you design it with component reusability in mind. If you created components that can be reused, you can package them into JAR files and add them to a reusable component repository. If you need a component, you may look into the repository for those components and then add them into your project or application. For example, you can create an application module for a domain and package it to be used as the data model project in several different applications. Or, if your application will be consuming components, you may be able to load a page template component from a repository of ADF Library JARs to create common look and feel pages. Then you can put your page flow together by stringing together several task flow components pulled from the library. An ADF Library JAR contains ADF components and does not, and cannot, contain other JARs. It should not be confused with the JDeveloper library, Java EE library, or Oracle WebLogic shared library. Reusable Component Description Data Control Any data control can be packaged into an ADF Library JAR. Some of the data controls supported by Oracle ADF include application modules, Enterprise JavaBeans, web services, URL services, JavaBeans, and placeholder data controls. Application Module When you are using ADF Business Components and you generate an application module, an associated application module data control is also generated. When you package an application module data control, you also package up the ADF Business Components associated with that application module. The relevant entity objects, view objects, and associations will be a part of the ADF Library JAR and available for reuse. Business Components Business components are the entity objects, view objects, and associations used in the ADF Business Components data model project. You can package business components by themselves or together with an application module. Task Flows & Task Flow Templates Task flows can be packaged into an ADF Library JAR for reuse. If you drop a bounded task flow that uses page fragments, JDeveloper adds a region to the page and binds it to the dropped task flow. ADF bounded task flows built using pages can be dropped onto pages. The drop will create a link to call the bounded task flow. A task flow call activity and control flow will automatically be added to the task flow, with the view activity referencing the page. If there is more than one existing task flow with a view activity referencing the page, it will prompt you to select the one to automatically add a task flow call activity and control flow. If an ADF task flow template was created in the same project as the task flow, the ADF task flow template will be included in the ADF Library JAR and will be reusable. Page Templates You can package a page template and its artifacts into an ADF Library JAR. If the template uses image files and they are included in a directory within your project, these files will also be available for the template during reuse. Declarative Components You can create declarative components and package them for reuse. The tag libraries associated with the component will be included and loaded into the consuming project. You can also package up projects that have several different reusable components if you expect that more than one component will be consumed. For example, you can create a project that has both an application module and a bounded task flow. When this ADF Library JAR file is consumed, the application will have both the application module and the task flow available for use. You can package multiple components into one JAR file, or you can package a single component into a JAR file. Oracle ADF and JDeveloper give you the option and flexibility to create reusable components that best suit you and your organization. You create a reusable component by using JDeveloper to package and deploy the project that contains the components into a ADF Library JAR file. You use the components by adding that JAR to the consuming project. At design time, the JAR is added to the consuming project's class path and so is available for reuse. At runtime, the reused component runs from the JAR file by reference.

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  • Google : "ne plus être soumis à la loi des États-Unis serait génial", son co-fondateur critique les plateformes fermées de Facebook et Apple

    Google : « ne plus être soumis à la loi des États-Unis, ce serait génial » Son co-fondateur critique Facebook et Apple et se dit « plus inquiet que jamais » pour l'ouverture d'Internet « La liberté sur Internet est en danger ». Cette déclaration alarmiste ne vient pas du Parti Pirate ou de l'Electronic Frontier Foundation mais d'un acteur beaucoup plus étonnant : Sergey Brin, un des deux co-fondateurs de Google. Dans un entretien au quotidien britannique The Guardian, le jeune dirigeant (38 ans) s'en prend pêle-mêle aux gouvernements qui essayent de contrôler l'expression des citoyens, aux associations d'auteurs/compositeurs qui sous prétexte, d'après lui, de lutter c...

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  • Soccer Game only with National Team names (country names) what about player names? [duplicate]

    - by nightkarnation
    This question already has an answer here: Legal issues around using real players names and team emblems in an open source game 2 answers Ok...this question hasn't been asked before, its very similar to some, but here's the difference: I am making a soccer/football simulator game, that only has national teams (with no official logos) just the country names and flags. Now, my doubt is the following...can I use real player names (that play or played on that national team?) From what I understand if I use a player name linked to a club like Barcelona FC (not a national team) I need the right from the club and the association that club is linked to, right? But If I am only linking the name just to a country...I might just need the permission of the actual player (that I am using his name) and not any other associations, correct? Thanks a lot in advance! Cheers, Diego.

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  • Why is Prolog associated with Natural Language Processing?

    - by kyphos
    I have recently started learning about NLP with python, and NLP seems to be based mostly on statistics/machine-learning. What does a logic programming language bring to the table with respect to NLP? Is the declarative nature of prolog used to define grammars? Is it used to define associations between words? That is, somehow mine logical relationships between words (this I imagine would be pretty hard to do)? Any examples of what prolog uniquely brings to NLP would be highly appreciated.

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  • Les ayants droit hantés par Megaupload ? Des demandes de suppression pleuvent encore sur Google pour des services disparus

    Les ayants droit hantés par Megaupload, Demonoid et BTjunkie ? Des demandes de suppression pleuvent encore sur Google pour des services qui n'existent plus [IMG]http://idelways.developpez.com/news/images/fbi.jpg[/IMG] Google reçoit quotidiennement une quantité importante de demandes de suppression de liens vers Megaupload, Demonoid et BTjunkie et autres services de partage mis hors service depuis déjà un moment ! Ces demandes proviennent des plus grandes maisons de disques ainsi que des compagnies et associations antipiratage, qui envoient des rapports DMCA (une loi américaine contre le copyright) sans même vérifier si ces liens existent toujours. ...

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