9865419
A compositional reasoning system for executing nonmonotonic theories of reasoning
In this paper the framework DESIRE for the design of compositional reasoning systems and multi-agent systems was applied to build a generic nonmonotonic reasoning system. The outcome is a general reasoning system that can be used to model different nonmonotonic reasoning formalisms and that can be executed by a generic execution mechanism. The main advantages of using DESIRE (for example, compared to a direct implementation in a programming language such as PROLOG) are that the design is generic and has a transparent compositional structure, and the explicit declarative specification of both the static and dynamic aspects of the nonmonotonic reasoning processes, including their control. © 2003 Wiley Periodicals, Inc.
5775307
Compositional Verification of Multi-Agent Systems in Temporal Multi-Epistemic Logic
Compositional verification aims at managing the complexity of the verification process by exploiting compositionality of the system architecture. In this paper we explore the use of a temporal epistemic logic to formalize the process of verification of compositional multi-agent systems. The specification of a system, its properties and their proofs are of a compositional nature, and are formalized within a compositional temporal logic: Temporal Multi-Epistemic Logic. It is shown that compositional proofs are valid under certain conditions. Finally, the possibility of incorporating default persistence of information in a system, is explored.
9686977
A Temporal Model Theory for Default Logic
By explicitly identifying the temporal aspect of a default rule as it is used in a reasoning process, it is argued that a natural semantic theory of Reiter's default logic is a temporal one. To be able to accommodate the lack of complete knowledge at any point in time, the temporal models should be partial models. A temporal partial logic is introduced, and it is shown that this logic can provide semantics for Reiter's default logic.
41515310
Minimal Temporal Epistemic Logic
15665579
Specification of Dynamics for Knowledge-Based Systems
During the last years, a number of formal specification languages for knowledge-based systems have been developed. Characteristic for knowledge-based systems are a complex knowledge base and an inference engine which uses this knowledge to solve a given problem. Specification languages for knowledge-based systems have to cover both aspects: they have to provide means to specify a complex and large amount of knowledge and they have to provide means to specify the dynamic reasoning behaviour of a knowledge-based system. This paper will focus on the second aspect, which is an issue considered to be unsolved. For this purpose, we have surveyed existing approaches in related areas of research. We have taken approaches for the specification of information systems (i.e., Language for Conceptual Modelling and Troll), approaches for the specification of database updates and the dynamics of logic programs (Transaction Logic and Dynamic Database Logic), and the approach of Abstract State Machines.
34555418
Nonmonotonic Reasoning with Multiple Belief Sets
In the present paper we introduce nonmonotonic belief set operators and selection operators to formalize and to analyze multiple belief sets in an abstract setting. We define and investigate formal properties of belief set operators as absorption, congruence, supradeductivity and weak belief monotony. Furthermore, it is shown that for each belief set operator satisfying strong belief cumulativity there exists a largest monotonic logic underlying it, thus generalizing a result for nonmonotonic inference operations. Finally, we study abstract properties of selective inference operations connected to belief set operators and which are used to choose one of the possible views.
14239266
The Equivalence Problem for Deterministic MSO Tree Transducers Is Decidable
It is decidable for deterministic MSO definable graph-to-string or graph-to-tree transducers whether they are equivalent on a context-free set of graphs.
30357320
The Power to Two-Way Deterministic Checking Stack Automata
Abstract It is well known that nondeterministic two-way checking stack automata recognize NSPACE( n ). We show that deterministic two-way checking stack automata have the same power as deterministic two-way two-head finite automata. The easy proof is based on the closure under inverse deterministic two-way GSM mappings of the deterministic two-way two-head finite automaton languages.
9307461
Context Free Normal Systems and ETOL Systems
Abstract The relationship between extended context free normal systems (a nondeterministic version of Tag systems of Post with deletion number equal to 1 and using nonterminals) and ETOL systems is considered. It is demonstrated that the class of languages generated by context free normal systems (denoted L (ECFN)) lies strictly between the clas of EOL languages (denoted L (EOL)) and the class of ETOL languages. Several characterizations of L (ECFN)) in terms of L (EOL)) are provided and a number of closure properties of L '(ECFN) are established.
17739753
Finite Languages for the Representation of Finite Graphs
We introduce a new way of specifying graphs: through languages, i.e., sets of strings. The strings of a given (finite, prefix-free) language represent the vertices of the graph; whether or not there is an edge between the vertices represented by two strings is determined by the pair of symbols at the first position in these strings where they differ. With this new, “positional” or lexicographic, method, classical and well-understood ways of specifying languages can now be used to specify graphs, in a compact way; thus, (small) finite automata can be used to specify (large) graphs. Since (prefix-free) languages can be viewed as trees, our method generalizes the hierarchical specification of particular types of graphs such as cographs and VSP graphs. Our main results demonstrate an intrinsic relationship between the fundamental operations of language concatenation and graph substitution.
17560850
Clique-Width for Four-Vertex Forbidden Subgraphs
Clique-width of graphs is a major new concept with respect to efficiency of graph algorithms. The notion of clique-width extends the one of treewidth, since bounded treewidth implies bounded clique-width. We give a complete classification of all graph classes defined by forbidden induced subgraphs of at most four vertices with respect to bounded or unbounded clique-width.