The paper investigates modal (temporal-model) logics based at a semantic approach with models combining knowledge and time. We introduce multi-modal logics LTKr and LTKir containing modalities for knowledge and time as the sets of all LTKr-valid, and LTKir-valid formulae for a class of special LTKrframes, LTKir-frames, respectively. The main results of this paper are theorems stating that LTKr ...

We establish that the quantifier alternation hierarchy of formulae of Second-Order Propositional Modal Logic (SOPML) induces an infinite corresponding semantic hierarchy over the class of finite directed graphs. This is a response to an open problem posed in [4] and [8]. We also provide modal characterizations of the expressive power of Monadic Second-Order Logic (MSO) and address a number of p...

The problem of model construction is known to be a very important one. An extension of semantic tableaux (that can also be applied to the matings and to the connection method) allowing the building of models in a systematic way is presented. This approach is diierent from the usual one in semantic tableaux, in which model construction is a by-product of refutation failures (and this only in ver...

In this paper we give a characterization of both Boolean and arithmetic circuit classes of logarithmic depth in the vein of descriptive complexity theory, i.e., the Boolean classes NC1, SAC1 and AC1 as well as their arithmetic counterparts #NC1, #SAC1 and #AC1. We build on Immerman’s characterization of constant-depth polynomial-size circuits by formulae of first-order logic, i.e., AC0 = FO, an...

Linear Temporal Logic (LTL) is a widely used specification framework for linear time properties of systems. The standard approach for verifying such properties is by transforming LTL formulae to suitable ω-automata and then applying model checking. We revisit Vardi’s transformation of an LTL formula to an alternating ω-automaton and Wolper’s LTL tableau method for satisfiability checking. We ob...

BACKGROUND AND AIM Many mothers consult physicians because of frequent infant regurgitation. Guidelines recommend reassurance and dietary treatment as first approaches. The aim of the present study was to test and compare the efficacy of 2 antiregurgitation formulae (ARF). METHODS A prospective, double-blind, randomized cross-over trial was performed for a 1-month period in 115 formula-fed in...

INTRODUCTION Lutzomyia intermedia s. s. and L. neivai, usually considered as belonging to just one species, constitute a complex of species. The measurements of several anatomical structures of specimens of both groups, from Brazil, Paraguay, Argentina and Bolivia were analysed. METHOD Thirty-nine structures were measured in specimens of both sexes, using a graduated ocular, analysing compari...

The feature interaction problem is prominent in telephone service development. Through a number of case studies, we have discovered that no single semantic framework is suitable for the synthesis and analysis of formal feature requirements models, and the choice of modelling language has certain knock-on effects on the transformational design steps which lead to implementation. We initially des...