Concurrent Prolog definition
variant with guarded clauses and committed-choice nondeterminism (don't-care nondeterminism) by Ehud "Udi" Shapiro, Yale firstname.lastname@example.org
. A subset has been implemented, but not the full language.
See also Mandala
["Concurrent Prolog: Collected Papers", E. Shapiro, V.1-2, MIT Press 1987].