Commutative zeropotent semigroups
Commutative zeropotent semigroups with few invariant congruences
Commutative semigroups satisfying the equation and having only two -invariant congruences for an automorphism group are considered. Some classes of these semigroups are characterized and some other examples are constructed.
Commutative zeropotent semigroups with few prime ideals
We construct an infinite commutative zeropotent semigroup with only two prime ideals.
Computing finite commutative semigroups.
Computing the integral closure of an affine semigroup.
Congruence monoids
Corrigendum: On linear algebraic semigroups. III.
Countable Hausdorff spaces with countable weight