3coSoKu and its declarative modeling

In this paper, we analyze the physical puzzle IcoSoKu, a game about placing some given triangular tiles on the faces of an icosahedron in order to fill the capacities of its vertices, and we propose its generalization called 3coSoKu, admitting an arbitrary playing field with triangular faces, arbitrary capacities and an arbitrary set of triangular tiles. First, we prove the strong NP-completeness of 3coSoKu, even when the playing field is a convex polyhedron with equilateral triangles as faces. Second, we encode 3coSoKu both in the constraint modeling language MiniZinc and in the logic programming paradigm known as Answer Set Programming and we develop a visual tool for an accessible interface to the solver. Finally, we use our encodings to verify experimentally that every initial state for IcoSoKu admits a solution.Peer reviewe

Dagstuhl News January - December 2011

"Dagstuhl News" is a publication edited especially for the members of the Foundation "Informatikzentrum Schloss Dagstuhl" to thank them for their support. The News give a summary of the scientific work being done in Dagstuhl. Each Dagstuhl Seminar is presented by a small abstract describing the contents and scientific highlights of the seminar as well as the perspectives or challenges of the research topic

Reasoning over Assumption-Based Argumentation Frameworks via Answer Set Programming

Formal argumentation is a vibrant research area within artificial intelligence, in particular in knowledge representation and reasoning. Computational models of argumentation are divided into abstract and structured formalisms. Since its introduction in 1995, abstract argumentation, where the structure of arguments is abstracted away, has been much studied and applied. Structured argumentation formalisms, on the other hand, contain the explicit derivation of arguments. This is motivated by the importance of the construction of arguments in the application of argumentation formalisms, but also makes structured formalisms conceptually and often computationally more complex than abstract argumentation. The focus of this work is on assumption-based argumentation (ABA), a major structured formalism. Specifically we address the relative lack of efficient computational tools for reasoning in ABA compared to abstract argumentation. The computational efficiency of ABA reasoning systems has been markedly lower than the systems for abstract argumentation. In this thesis we introduce a declarative approach to reasoning in ABA via answer set programming (ASP), drawing inspiration from existing tools for abstract argumentation. In addition, we consider ABA+, a generalization of ABA that incorporates preferences into the formalism. The complexity of reasoning in ABA+ is higher than in ABA for most problems. We are able to extend our declarative approach to some ABA+ reasoning problems. We show empirically that our approach vastly outperforms previous reasoning systems for ABA and ABA+

Towards designing a knowledge-based tutoring system : SQL-tutor as an example

A Knowledge-Based Tutoring System, also sometimes called an Intelligent Tutoring System, is a computer based instructional system that uses artificial intelligence techniques to help people learn some subject. The goal of the system is to provide private tutoring to its students based on their different backgrounds, requests, and interests. The system knows what subject materials it should teach, when and how to teach them, and can diagnose the mistakes made by the students and help them correct the mistakes. The major objective of this dissertation is to investigate and develop a generic framework upon which we can build a Knowledge-Based Tutoring System effectively. As an example, we have focused on developing SQL-TUTOR, a tutoring system for teaching SQL concepts and programming skills. The generic architecture of the system is rooted at the popular view that a tutoring process between a tutor (either a human being or a machine) and a student is a knowledge communication process. This process can be divided into a series of communication cycles and each communication cycle consists of four phases, namely, planning, discussing, evaluating, and remedying phases. One major feature of the architecture proposed by us in this dissertation is its curriculum knowledge base which contains the knowledge about the course curriculum, We have developed a representation schema for describing the goal structure of the course, the prerequisite relationships among the course materials, and the multiple views to organize these materials. The inclusion of the curriculum knowledge in a KBTS allows the system to create different curricula for each individual student and to diagnose the student\u27s errors more effectively. The system also provides a group of operators for the student to hand-tailor his/her curricula when he/she starts learning the course. The student can use these operators to select a specific path to go through the course materials, to pick a specific topic from the curricula to study, or to remove a particular topic from the curricula. Since the student can construct his/her own learning plans by these operators, he/she is relatively free to determine how to study the course materials and, as a result, he/she can become more active in the tutoring process. The knowledge about a subject domain is stored in a set of topics and a sample database. The content of a topic consists of a set of related domain concepts. Each concept is described by both natural and formal forms. The relationships among the concepts are modeled a type of semantic network called the context network. The sample database contains a set of sample tables and an enhanced system catalog which contains the knowledge about the name, semantic meanings of the database objects. The built-in Problem Solver of the system allows the system to reason over the networks and the sample database and answer various kinds of questions raised by the student about the domain concepts and their relationships. The knowledge of writing SQL queries is embodied in a set of examples attached to the topics. Each of such an example is carefully designed for one category of SQL query problems. An example in SQL-TUTOR is a packed knowledge chunk which can serve several important teaching purposes, including generating problem descriptions with different levels of details, formulating various SQL solutions for the given problem, explaining these solutions to the student, and evaluating SQL queries written by the student

Dagstuhl News January - December 2002

"Dagstuhl News" is a publication edited especially for the members of the Foundation "Informatikzentrum Schloss Dagstuhl" to thank them for their support. The News give a summary of the scientific work being done in Dagstuhl. Each Dagstuhl Seminar is presented by a small abstract describing the contents and scientific highlights of the seminar as well as the perspectives or challenges of the research topic