Strong fairness and ultra metrics

AbstractWe answer an open question of Costa and Hennessy and present a characterization of the infinite fair computations in finite labeled transition systems—without any structure of the states—as cluster points in metric spaces. This technique is applied to reduce the logical complexity of several known fairness concepts from Π03 to Π02 and from Σ11 to Π03, respectively

Some Examples of Semi-rational and Non-semi-rational DAG Languages. Extended Version

The class of semi-rational dag (d irected acyclic graph) languages can be equivalently characterized by labeled Petri nets with ε-transitions, by rather simple leave substituting tree grammars with additional non-local merge rules, or as a synchronization closure of Courcelles class of recognizable sets of unranked, unordered trees. However, no direct recognition by some magma is known. For a better understanding, we present here some examples of languages within and without the class of semi-rational dag languages.

Fast and Robust Segmentation of Natural Color Scenes

This paper describes our entire color segmentation system, called CSC (Color Structure Code), in detail. In section 2 we introduce the hexagonal, hierarchical island structure on which our method is based. Section 3 describes the actual segmentation method. In Section 4 the new color similarity measure is presented. Section 5 discusses the complexity of our approach. The system is very fast and thus applicable in real world problems. Finally we present some results and conclusions in section 6. 2 Hexagonal, hierarchical island structur