András Z. Salamon

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a r t i c l e i n f o a b s t r a c t The Constraint Satisfaction Problem (CSP) is a central generic problem in artificial intelligence. Considerable progress has been made in identifying properties which ensure tractability in such problems, such as the property of being tree-structured. In this paper we introduce the broken-triangle property, which allows(More)
By using recent results from graph theory, including the Strong Perfect Graph Theorem, we obtain a unifying framework for a number of tractable classes of constraint problems. These include problems with chordal microstructure; problems with chordal microstructure complement; problems with tree structure; and the " all-different " constraint. In each of(More)
The constraint satisfaction problem (CSP) is a general problem central to computer science and artificial intelligence. Although the CSP is NP-hard in general, considerable effort has been spent on identifying tractable subclasses. The main two approaches consider structural properties (restrictions on the hypergraph of constraint scopes) and relational(More)
The constraint satisfaction problem (CSP) is a central generic problem in artificial intelligence. Considerable progress has been made in identifying properties which ensure tractability in such problems, such as the property of being tree-structured. In this paper we introduce the broken-triangle property, which allows us to define a hybrid tractable class(More)
We study the problem of query containment of (unions of) conjunctive queries over annotated databases. Annotations are typically attached to tuples and represent metadata such as probability, multiplicity, comments, or provenance. It is usually assumed that annotations are drawn from a commutative semiring. Such databases pose new challenges in query(More)
We study the problem of query containment of conjunctive queries over annotated databases. Annotations are typically attached to tuples and represent metadata, such as probability, multiplicity, comments, or provenance. It is usually assumed that annotations are drawn from a commutative semiring. Such databases pose new challenges in query optimization,(More)
We introduce a new model of collective decision making , when a global decision needs to be made but the parties only possess partial information, and are unwilling (or unable) to first create a global composite of their local views. Our macroscope model captures two key features of many real-world problems: allotment structure (how access to local(More)
In this thesis I study constraint satisfaction problems or CSPs. These require determining whether values can be assigned to variables so that all constraints are satisfied. An important challenge is to identify tractable CSPs which can be solved efficiently. CSP instances have usually been grouped together by restricting either the allowed combinations of(More)
Perhaps you're a computer scientist wondering how much the Axiom of Choice matters to the theorems you study and prove [ 21]. Perhaps you're a mathematician who needs a top expert to explain what "randomness" really means in computability and complexity [ 16]. Perhaps you need a list of problems that can be used to show polynomial-time hardness results [(More)