(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.
ftp://nexus.yorku.ca/pub/scheme/scm/bevan.shar .
["Constraint Programming Languages - Their Specification and Generation", W. Leler, A-W 1988, ISBN 0-201-06243-7].