XII.—The Lattice of Congruences on a Bisimple ω-Semigroup
Walter Douglas Munn · Proceedings of the Royal Society of Edinburgh Section A Mathematical and Physical Sciences · 1967
Synopsis A necessary and sufficient condition is determined for the modularity of the lattice of congruences on a bisimple inverse semigroup whose semilattice of idempotents is order-anti-isomorphic to the set of natural numbers.