DISCO: A Web-Based Implementation of Discussion Games for Grounded and Preferred Semantics

One of the advantages of formal argumentation theory as a way of defining nonmonotonic inference is that it applies concepts that are close to human reasoning, like arguments and discussion. In recent years, various discussion games for formal argumentation have been stated [2]. The idea is that these discussion games can be used as proof procedures for the different argumentation semantics. That is, an argument is accepted with respect to a particular semantics iff it is possible to win the associated discussion game.2 This makes it possible to use the discussion games for the purpose of explanation. Instead of simply mentioning that an argument is in, say, the grounded extension, the computer can allow the user to raise objections (counter arguments) and address these (using counter counter arguments) after which the user is again allowed to raise objections, etc. The aim is that at some moment, all the user’s potential objections have been uttered and addressed, and that the user is ready to accept the argument the discussion started with. Our current demonstrator DISCO3 (DIscussion COmputation) provides a web-based implementation of the Preferred Game [3] and of the Grounded Discussion Game [1].4 The demonstrator is based entirely on Javascript, and all computation is performed at client side. On starting, the user can either open an existing argumentation framework (which uses a JSON based file format) or construct one manually by adding arguments and attacks to an initially empty canvas. Once the argumentation framework has been defined, the user can play either the preferred game or the grounded discussion game.