Two Techniques in the Area of the Star Problem

This paper deals with decision problems related to the star problem in trace monoids, which means to determine whether the iteration of a recognizable trace language is recognizable. Due to a theorem by G. Richomme from 1994 [32, 33], we know that the star problem is decidable in trace monoids which do not contain a submonoid of the form {a,c}* x {b,d}*. Here, we consider a more general problem: Is it decidable whether for some recognizable trace language and some recognizable or finite trace language P the intersection R ∩ P* is recognizable? If P is recognizable, then we show that this problem is decidale iff the underlying trace monoid does not contain a submonoid of the form {a,c}* x b*. In the case of finite languages P, we show several decidability and undecidability results

Neokorporacjonizm w Unii Europejskiej

"Korporacjonizm, który rozwinął się w niektórych systemach faszystowskich i autorytarnych w pierwszej połowie XX w., w latach powojennych uznany został za związany z tymi systemami i jako taki zasadniczo stracił na znaczeniu w życiu politycznym, społecznym oraz gospodarczym Europy. Jednakże oprócz odrzuconej postaci autorytarnej, korporacjonizm nadal wpływał na kształt ustrojów państwowych, ale już jako demokratyczny czynnik znany w formie korporacjonizmu społecznego."(...

All-Instances Restricted Chase Termination

The chase procedure is a fundamental algorithmic tool in database theory with a variety of applications. A key problem concerning the chase procedure is all-instances termination: for a given set of tuple-generating dependencies (TGDs), is it the case that the chase terminates for every input database? In view of the fact that this problem is undecidable, it is natural to ask whether known well-behaved classes of TGDs ensure decidability. We consider here the main paradigms that led to robust TGD-based formalisms, that is, guardedness and stickiness. Although all-instances termination is well-understood for the oblivious version of the chase, the more subtle case of the restricted (a.k.a. the standard) chase is rather unexplored. We show that all-instances restricted chase termination for guarded and sticky single-head TGDs is decidable