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pro vyhledávání: '"Šemrl, Jaš"'
A semigroup of binary relations (under composition) on a set $X$ is \emph{complemented} if it is closed under the taking of complements within $X\times X$. We resolve a 1991 problem of Boris Schein by showing that the class of finite unary semigroups
Externí odkaz:
http://arxiv.org/abs/2410.15906
Autor:
Jipsen, Peter, Šemrl, Jaš
A binary relation defined on a poset is a weakening relation if the partial order acts as a both-sided compositional identity. This is motivated by the weakening rule in sequent calculi and closely related to models of relevance logic. For a fixed po
Externí odkaz:
http://arxiv.org/abs/2301.02213
Autor:
Šemrl, Jaš
The decision problem of membership in the Representation Class of Relation Algebras (RRA) for finite structures is undecidable. However, this does not hold for many Relation Algebra reduct languages. Two well known properties that are sufficient for
Externí odkaz:
http://arxiv.org/abs/2111.01213
Autor:
Šemrl, Jaš
Relational semigroups with domain and range are a useful tool for modelling nondeterministic programs. We prove that the representation class of domain-range semigroups with demonic composition is not finitely axiomatisable. We extend the result for
Externí odkaz:
http://arxiv.org/abs/2106.02709
Autor:
Hirsch, Robin, Šemrl, Jaš
Relation algebra and its reducts provide us with a strong tool for reasoning about nondeterministic programs and their partial correctness. Demonic calculus, introduced to model the behaviour of a machine where the demon is in control of nondetermini
Externí odkaz:
http://arxiv.org/abs/2105.06787
Autor:
Hirsch, Robin, Šemrl, Jaš
Composition and demonic refinement $\sqsubseteq$ of binary relations are defined by \begin{align*} (x, y)\in (R;S)&\iff \exists z((x, z)\in R\wedge (z, y)\in S) R\sqsubseteq S&\iff (dom(S)\subseteq dom(R) \wedge R\restriction_{dom(S)}\subseteq S) \en
Externí odkaz:
http://arxiv.org/abs/2009.06970