Conceptual Information Compression and Efficient Pattern Search

This paper introduces an encoding of knowledge representation statements as regular languages and proposes a two-phase approach to processing of explicitly declared conceptual information. The idea is presented for the simple conceptual graphs where conceptual pattern search is implemented by the so called projection operation. Projection calculations are organised into off-line preprocessing and run-time computations. This enables fast run-time treatment of NP-complete problems, given that the intermediate results of the off-line phase are kept in suitable data structures. The experiments with randomly-generated, middle-size knowledge bases support the claim that the suggested approach radically improves the run-time conceptual pattern search

Incremental construction of minimal acyclic finite-state automata

In this paper, we describe a new method for constructing minimal, deterministic, acyclic finite-state automata from a set of strings. Traditional methods consist of two phases: the first to construct a trie, the second one to minimize it. Our approach is to construct a minimal automaton in a single phase by adding new strings one by one and minimizing the resulting automaton on-the-fly. We present a general algorithm as well as a specialization that relies upon the lexicographical ordering of the input strings.Comment: 14 pages, 7 figure

Direct Construction of Minimal Acyclic Finite States Automata

This paper presents automaton construction algorithms based on the method for direct building of minimal acyclic finite states automaton for a given list [Mi98]. A detailed presentation of the base algorithm with correctness and complexity proofs is given. The memory complexity of the base algorithm is O(m) and the worst-case time complexity is O(n log(m)), where n is the total number of letters in the input list, m is the size of the resulting minimal automaton. Further we present algorithms for direct construction of minimal automaton presenting the union, intersection and difference of acyclic automata. In the cases of intersection and difference only the first input automaton has to be acyclic. The memory complexity of those construction algorithms is O(m), and the time complexity is O(n log(m)) for union and O(n1 + n log(m)) for intersection and difference, where n1 is the total number of letters in the first automaton language, n is the number of all letters in the resulting aut..

Co-Regular Languages and Unification of Co-Regular Languages

. The main goal of this work is the investigation of some properties of co-regular languages. In many applications it is important to handle infinite sets of terms. We represent two equivalent formalisms for finite defined infinite sets of term substitutions which are leading to co-regular languages. As it will be proved later the co-regular languages are monoidic homomorphical images of regular languages. A natural definition of unification of co-regular languages is introduced. This paper is a compressed version of [Mi93]. 1 Monoids In this section we present a brief introduction in the monoid theory. Definition1. A monoid M (semigroup with unit element) is the triple hM; ffi; ei where: -- M is the set of monoid elements; -- ffi : M \Theta M !M is the monoid operation (we will use infix notation); -- e 2 M is the monoid unit element, and the following conditions hold: -- 8a; b; c 2 M (a ffi (b ffi c) = (a ffi b) ffi c) (associativity), -- 8a 2 M (a ffi e = e ffi a = a). Examp..

A Constraint Based System for Lexical Knowledge Retrieval

This paper is concerned with the lexical knowledge retrieval system created at the Linguistic Modelling Laboratory. The main goal of the system is to provide a powerful and comfortable interface for lexical knowledge retrieval from large morphological dictionary. To achieve this a constraint based approach is applied that leads to a very effective algorithm. The algorithm for query building, which is also used for retrieving of general grammatical knowledge, is presented in details. In our opinion this method is very suitable for knowledge retrieval in domains with complex and irregular classifications. 1 Introduction Recently, many systems containing large amount of lexical knowledge have been built. They make use of different approaches for processing and knowledge representation. Detailed study of the problem is presented in [Pu95] and [Br92]. The Linguistic Modelling Laboratory is working on a Large Morphological Dictionary that will cover most of the wordforms in modern Bulgarian..

Direct Building of Minimal Automaton for Given List

This paper presents a method for direct building of minimal acyclic finite states automaton which recognizes a given finite list of words in lexicographical order. The size of the temporary automata which are necessary for the construction is less than the size of the resulting minimal automata plus the length of one of the longest words in the list. This property is the main advantage of our method. 1 Intoduction The standard methods for building minimal finite states (FS) automaton are building temporary automata which generally are huge compared to the resulting minimal automaton. This grounds the interest in the development of more direct methods. Building an acyclic minimal FS automaton that recognizes a given list sorted in lexicografical order is of special interest for practical applications. A linear algorithm for that case is presented in [Re91, Re92]. The Revuz' method in the first stage builds a tree-like deterministic FS automaton. Then at the second stage this automaton ..