Geometrical regular languages and linear Diophantine equations: The strongly connected case

AbstractGiven an arbitrarily large alphabet Σ, we consider the family of regular languages over Σ for which the deterministic minimal automaton has a strongly connected state diagram. We present a new method for checking whether such a language is semi-geometrical or not and whether it is geometrical or not. This method makes use of the enumeration of the simple cycles of the state diagram. It is based on the construction of systems of linear Diophantine equations, where the coefficients are deduced from the set of simple cycles

Reducing Acyclic Cover Transducers

International audienceFinite languages and finite subsequential functions can be represented by possibly cyclic finite machines, respectively called cover automata and cover transducers. In general, reduced cover machines have much fewer states than the corresponding minimal machines, yielding a compact representation for lexicons or dictionaries. We present here a new algorithm for reducing the number of states of an acyclic transducer

Similarity relations and cover automata

Cover automata for finite languages have been much studied a few years ago. It turns out that a simple mathematical structure, namely similarity relations over a finite set of words, is underlying these studies. In the present work, we investigate in detail for themselves the properties of these relations beyond the scope of finite languages. New results with straightforward proofs are obtained in this generalized framework, and previous results concerning cover automata are obtained as immediate consequences

Algorithms for the Join and Auto-Intersection of Multi-Tape Weighted Finite-State Machines.

International audienceA weighted finite-state machine with n tapes describes a rational relation on n strings. We recall some basic operations on n-ary rational relations, recast the important join operation in terms of "auto-intersection", and propose restricted algorithms for both operations. If two rational relations are joined on more than one tape, it can unfortunately lead to non-rational relations with undecidable properties. As a consequence, there cannot be a fully general algorithm, able to compile any rational join or auto-intersection. We define a class of triples 〈A,i,j〉 for which we are able to compile the auto-intersection of the machine A w.r.t. tapes i and j. We hope that this class is sufficient for many practical applications

Geometrical Regular Languages and Linear Diophantine Equations

International audienceWe present a new method for checking whether a regular language over an arbitrarily large alphabet is semi-geometrical or whether it is geometrical. This method makes use first of the partitioning of the state diagram of the minimal automaton of the language into strongly connected components and secondly of the enumeration of the simple cycles in each component. It is based on the construction of systems of linear Diophantine equations the coefficients of which are deduced from the the set of simple cycles. This paper addresses the case of a strongly connected graph

Geometrical Regular Languages and Linear Diophantine Equations

International audienceWe present a new method for checking whether a regular language over an arbitrarily large alphabet is semi-geometrical or whether it is geometrical. This method makes use first of the partitioning of the state diagram of the minimal automaton of the language into strongly connected components and secondly of the enumeration of the simple cycles in each component. It is based on the construction of systems of linear Diophantine equations the coefficients of which are deduced from the the set of simple cycles. This paper addresses the case of a strongly connected graph

A class of rational n-WFSM auto-intersections

Abstract. Weighted finite-state machines with n tapes describe n-ary rational string relations. The join n-ary relation is very important in applications. It is shown how to compute it via a more simple operation, the auto-intersection. Join and auto-intersection generally do not preserve rationality. We define a class of triples 〈A, i, j 〉 such that the auto-intersection of the machine A on tapes i and j can be computed by a delay-based algorithm. We point out how to extend this class and hope that it is sufficient for many practical applications.