The trace equivalence of BPP was shown to be undecidable by Hirshfeld. We show that the trace equivalence remains undecidable even if the number of labels is restricted to two. The undecidability result holds also for the simulation of two-label BPP processes. These results imply undecidability of some behavioral type systems for the π-calculus.

In this paper we first give a one-move version of Markov’s braid theorem for knot isotopy in S that sharpens the classical theorem. Then a relative version of Markov’s theorem concerning a fixed braided portion in the knot. We also prove an analogue of Markov’s theorem for knot isotopy in knot complements. Finally we extend this last result to prove a Markov theorem for links in an arbitrary or...

One of the challenges in analyzing the strategies in contract bridge stems from the fact that it is a Bayesian game with a very large type space, and that players’ action sets depend on their type. This results in a the strategy space being of a size where brute force methods of analysis are not practical. We present a general approach to simplifying this strategy space through the use of equiv...

In this paper there is proposed a method of partition the attributes of relation scheme in equivalence classes and in nonredundant equivalence classes. Several properties of these equivalence classes are proved. Their properties serve as the basis for an algorithm with a polynomial complexity, which determines the prime attributes of a database schema.

This paper presents a new property between processes arising from a set of relations called weak conformations. The largest, called weak conformance, is analogous to Milner’s observational equivalence. Unlike observational equivalence, however, weak conformance is not an equivalence but rather a preorder between processes. Like the previous property of logic conformance, weak conformance allows...

Given a measurable space (X ,M ) there is a (Galois) connection between sub-σ -algebras of M and equivalence relations on X . On the other hand equivalence relations on X are closely related to congruences on stochastic relations. In recent work, Doberkat has examined lattice properties of posets of congruences on a stochastic relation and motivated a domain-theoretic investigation of these ord...

This paper focuses on the preservation of the period in the periodic Kalman canonical decomposition with complex-valued coefficients. This clarifies essential difference between linear periodic systems with real-valued coefficients and with complex-valued coefficients.

Non{Abelian duality in relation to supersymmetry is examined. When the action of the isometry group on the complex structures is non{trivial, extended supersymmetry is realized non{locally after duality, using path ordered Wilson lines. Prototype examples considered in detail are, hyper{Kahler metrics with SO(3) isometry and supersymmetric WZW models. For the latter, the natural objects in the ...