LOTOS is a formal specification language, designed for the precise description of open distributed systems and protocols. The definition of, so called, implementation relations has made it possible also to use LOTOS as a specification technique for the design of such systems. These LOTOS based specification techniques usually (ab)use non-determinism to achieve implementation freedom. Unfortunat...

This paper concerns what might be called the variably bad behavior of the word or. As is well known, there are a variety of environments in which the word or misbehaves – misbehaves, in the sense that it gives rise to interpretations which are not expected given the standard analysis of this word as, roughly, set union. One of these environments is the scope of a modal. This case has received a...

We investigate fragments of intuitionistic propositional logic containing implication but not disjunction. These fragments are finite, but their size grows superexponentially with the number of generators. Exact models are used to characterize the fragments.

It is now common practice to use structured sets of features to describe syntactic structures, and to compare such structured sets by some form of unification. It is extremely tempting to try to encode disjunctive information within this framework; unfortunately, general unification of disjunctive structures is NPcomplete, which is not a desirable property for the basic operation involved in co...

The quest ion of whether concepts expressible as d is junc t ions of conjunct ions can be learned from examples in polynomial t ime is i nves t i ga ted . Pos i t i ve resu l t s are shown fo r s i g n i f i c a n t sub­ classes tha t a l low not only p ropos i t i ona l p re ­ d icates but also some r e l a t i o n s . The algori thms are extended so as to be provably t o l e ran t to a ce r t...

We study the expressive power of various modal logics with team semantics. We show that exactly the properties of teams that are downward closed and closed under team k-bisimulation, for some finite k, are definable in modal logic extended with intuitionistic disjunction. Furthermore, we show that the expressive power of modal logic with intuitionistic disjunction and extended modal dependence ...

We equip ordered logic programs with negation as failure, using a simple generalization of the preferred answer set semantics for ordered programs. This extension supports a convenient formulation of certain problems, which is illustrated by means of an intuitive simulation of logic programming with ordered disjunction. The simulation also supports a broader application of “ordered disjunction”...