(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. Ef="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].