We formalize a unified framework for verified decision procedures for regular expression equivalence. Five recently published formalizations of such decision procedures (three based on derivatives, two on marked regular expressions) can be obtained as instances of the framework. We discover that the two approaches based on marked regular expressions, which were previously thought to be the same...

An associate inverse subsemigroup of a regular semigroup S is a subsemigroup T of S containing a least associate x∗ of each x ∈ S, in relation to the natural partial order ≤S in S. In [1] the authors describe the structure of regular semigroups with an associate inverse subsemigroup, satisfying two natural conditions. In this paper we describe all ∗-congruences on such class of semigroups.

This theory defines deterministic and nondeterministic automata in a functional representation: the transition function/relation and the finality predicate are just functions. Hence the state space may be infinite. It is shown how to convert regular expressions into such automata. A scanner (generator) is implemented with the help of functional automata: the scanner chops the input up into long...

The relationship between space vector modulation and regular-sampled PWM techniques for hard-switching PWM inverters and rectifiers are reexamined in this paper. Space vector modulation with optimized apportioning of null vector time that results in minimum current THD is investigated and is compared with previously known methods. The conventional optimal regular-sampled PWM method and its rela...

The tree automaton completion is an algorithm used for proving safety properties on systems which can be modeled by a term rewriting system. This representation and verification technique works well for proving properties on infinite systems like cryptographic protocols or more recently on Java Bytecode programs. This algorithm computes a tree automaton which represents a (regular) over approxi...

INTRODUCTION Ebola virus disease (EVD) is a highly contagious viral infection that requires a high risk perception and practice of good hand hygiene by regular hand washing or use of hand sanitizers for infection control at all time. The declaration of Nigeria as an Ebola-free country by the World Health Organization on the 20th of October, 2014 has prompted many Nigerians, including healthcare...

This paper discusses on several variants of a fascinating problem of deciding whether two nite substitutions are equivalent on a regular language, as well as its relations to the equivalence problems of sequential transducers. Among other things it is proved to be decidable whether for a regular language L and two substitutions ' and , the latter one being a pre x substitution, the relation '(w...

Ten years ago, Dobrushin [1] proved a beautiful result showing that under suitable hypotheses, a statistical mechanical lattice system interaction has a unique equilibrium state. In particular, there is no long range order, etc. see [6,7] for related material, Israel [4] for analyticity results and Gross [3] for falloff of correlations. There does not appear to have been systematic attempts to ...