A language L A is literally idempotent in case that ua2 v L if and only if uav L, for each u, v A , a A. Varieties of literally idempotent languages result naturally by taking...
—The access of information systems to underlying relational databases is commonly programmed using embedded SQL queries. Such embedded queries may take the form of string literal...
Huib van den Brink, Rob van der Leek, Joost Visser