We present an algorithmically efficient criterion of modal definability for first-order existential conjunctive formulas with several free variables. Then we apply it to establish modal definability of some family of first-order ∀∃-formulas. Finally, we use our definability results to show that, in any expressive description logic, the problem of answering modally definable conjunctive queries ...

We use results on modal definability of first-order formulas to reduce the problem of answering conjunctive queries over knowledge bases (of any expressivity) to checking inconsistency of those knowledge bases extended with a number of ALCI concept assertions. This reduction has been shown to work for conjunctive queries without cycles that only involve bound variables. In this paper, we presen...

This paper introduces a new family of automata that turns out to be computationally equivalent to linear conjunctive grammars. Although, if viewed as a practical tool for describing practical languages, these automata are not nearly as convenient as linear conjunctive grammars are, they can be reasonably expected to be highly suitable for use in applications as a low-level computational model, ...

This paper investigates two aspects of using Fuzzy Logic with a GIS: The use of non-conventional aggregation operators for conjunctive and disjunctive reasoning and the use of weights when combining aggregates of different significance to the classification. Two methods of weighting are used, weights as powers of the membership functions, and the novel concept of membership functions that take ...

This paper presents a method to enhance a Chinese parser in parsing conjunctive structures. Long conjunctive structures cause long-distance dependencies and tremendous syntactic ambiguities. Pure syntactic approaches hardly can determine boundaries of conjunctive phrases properly. In this paper, we propose a divide-andconquer approach which overcomes the difficulty of data-sparseness of the tra...