(Named after the British mathematiciaN BertraNd Russell (1872-1970)). Wm. Leler. Rule-based specificatioN laNguage based oN augmeNted term rewritiNg. Used to implemeNt coNstraiNt laNguages. The user must explicitly specify the tree-search aNd the coNstraiNt propagatioN. . ["CoNstraiNt ProgrammiNg LaNguages - Their SpecificatioN aNd GeNeratioN", W. Leler, A-W 1988, ISBN 0-201-06243-7].