7 papers
Streaming algorithms for groups and semigroups
Markus Lohrey, Lukas Lück, Alexander Thumm +1
We investigate deterministic and randomized streaming algorithms for word problems in finitely generated groups and semigroups. For this we introduce the notion of a distinguisher:…
Quadratic Equations in Graph Products of Groups and the Exponent of Periodicity
Volker Diekert, Silas Natterer, Alexander Thumm
In 1977, Makanin established the decidability of equations in free monoids. A key ingredient in his proof is the exponent of periodicity: for a word , it is the largest exponent…
Efficient Compression in Semigroups
Alexander Thumm, Armin WeiÃ
Straight-line programs are a central tool in several areas of computer science, including data compression, algebraic complexity theory, and the algorithmic solution of algebraic e…
Quadratic word equations with regular constraints and the exponent of periodicity
Volker Diekert, Silas Natterer, Alexander Thumm
In this article, we study word equations in free semigroups and the conjecture that the existence of infinitely many solutions entails the existence of solutions with arbitrarily l…
Finite Semigroups Satisfying an Identity
Alexander Thumm
We determine the maximal pseudovarieties of finite semigroups that satisfy an identity of the form . Applying this classification, we fur…
Membership and Conjugacy in Inverse Semigroups
Lukas Fleischer, Florian Stober, Alexander Thumm +1
The membership problem for an algebraic structure asks whether a given element is contained in some substructure, which is usually given by generators. In this work we study the me…