Janusz Konieczny, professor of mathematics, gave a talk, Maximal Commutative Subsemigroups of a Finite Semigroup, at the AMS Special Session on Recent Trends in Semigroup Theory, at the Joint Mathematics Meetings, Denver Colorado, January 2020. The talks at the special session were by invitation only. Konieczny’s talk contained the research done during the sabbatical leave in the fall of 2017.