EQUATIONAL PROPERTY OF CERTAIN TRANSFORMATION MONOIDS
Jian Rong Li, Yanfeng Luo · International Journal of Algebra and Computation · 2010
The monoid of extensive transformations of a chain of order four is shown to be finitely based and a finite basis for this monoid is given. This completes the description of the equational property of the monoids of all full extensive transformations, partial extensive transformations, and partial order-preserving extensive transformations over any finite chain.