In this paper we present logical characterizations of two preorders, within the framework of Hennessy-Milner Logics. The two preorders (loosely termed bisimulation-based efficiency preorders) are on processes represented as labelled transition systems. The characterizations are particularly interesting as they explore preorders lying between strong and weak bisimilarity, guided by a principle o...

A new distance function dist (A,B) for fuzzy sets A and B is introduced. It is based on the descriptive complexity, i.e., the number of bits (on average) that are needed to describe an element in the symmetric difference of the two sets. The distance gives the amount of additional information needed to describe any one of the two sets given the other. We prove its mathematical properties and pe...

Syntactic constraints in Koskenniemi's Finite-State Intersection Grammar (FSIG) are logically less complex than their formalism (Koskenniemi et al., 1992) would suggest: It turns out that although the constraints in Voutilainen's (1994) FSIG description of English make use of several extensions to regular expressions, the description as a whole reduces to a finite combination of union, compleme...

We investigate the complexity of the xed-points of bounded formulas in the context of nite set theory; that is, in the context of arbitrary classes of nite structures that are equipped with a built-in BIT predicate, or equivalently, with a built-in membership relation between hereditarily nite sets (input relations are allowed). We show that the iteration of a positive bounded formula converges...