3 papers
math.RA2020
Reflections and powers of multisorted minions
Erkko Lehtonen, Reinhard Pöschel
Classes of multisorted minions closed under extensions, reflections, and direct powers are considered from a relational point of view. As a generalization of a result of Barto, Opr…
math.RA2019
Graph quasivarieties
Erkko Lehtonen, Reinhard Pöschel
Introduced by C. R. Shallon in 1979, graph algebras establish a useful connection between graph theory and universal algebra. This makes it possible to investigate graph varieties…
math.GR2012
Invariance groups of finite functions and orbit equivalence of permutation groups
Eszter K. Horváth, Géza Makay, Reinhard Pöschel +1
Which subgroups of the symmetric group S_n arise as invariance groups of n-variable functions defined on a k-element domain? It appears that the higher the difference n-k, the more…