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.