Wolfram Bentz

The commuting graph of a finite non-commutative semigroup S, denoted G(S), is a simple graph whose vertices are the non-central elements of S and two distinct vertices x,y are adjacent if xy=yx. This definition generalizes the corresponding concept...

Suppose you have a fixed number of boxes with a square base. These are transported in containers that also have a square base. In order to save space one wants to make containers small while still being able to hold all boxes. How large would the...

Natural dualities, such as Stone duality, are useful because they allow one to translate algebraic questions into the potentially simpler and usually more intuitive setting of a topological structure. Dualities are also tricky, in the sense that it...