1.Department of Algebra and Geometry, Faculty of Science,Palacky University Olomouc,Olomouc,Czech Republic;2.Faculty of Mathematics and Geoinformation, Institute of Discrete Mathematics and Geometry,TU Wien,Vienna,Austria
Abstract:
We prove that the variety ({{mathscr {V}}}) of commutative multiplicatively idempotent semirings satisfying (x+y+xyzapprox x+y) is generated by a single three-element semiring. Moreover, we describe a normal form system for terms in ({{mathscr {V}}}) and we show that the word problem in ({{mathscr {V}}}) is solvable. Although ({{mathscr {V}}}) is locally finite, it is residually big.