Pre-solid varieties of semigroups
Klaus-Dieter Denecke, Jörg Koppitz · Czech digital mathematics library · 1995
summary:Pre-hyperidentities generalize the concept of a hyperidentity. A variety $V$ is said to be pre-solid if every identity in $V$ is a pre-hyperidentity. Every solid variety is pre-solid. We consider pre-solid varieties of semigroups which are not solid, determine the smallest and the largest of them, and some elements in this interval.