A characterization of left cancellative monoids by flatness properties.
A characterization of regular monoids by flatness of left acts.
Absolute flatness of regular semigroups with a finite height function.
An equivalence theorem for inverse semigroups.
An example of two von Neumann regular rings with nonisomorphic Monta equivalent multiplicative semigroups.
Arithmetic infinite Grassmannians and the induced central extensions.
Bicategories of partial maps
Bijective reflexions and coreflexions of commutative unars
Biregular semigroups. I
Cancellative actions
The following problem is considered: when can the action of a cancellative semigroup on a set be extended to a simply transitive action of the universal group of on a larger set.
Categories of Semigroups with Divisor Theory
Characterization of monoids by condition (P) of cyclic left acts.
Closure operations and semigroups of quotients
Cohomology groups of a groupoid.
Colimits of representable algebra-valued functors.
Commutative semigroup cohomology.
Commutative semigroups with few fully invariant congruences I.
Commutative semigroups with few fully invariant congruences II.
Complementation and inner automorphism regular semigroups.
Completely quasi-projective monoids.