Source : Free On-Line Dictionary of Computing

Constraint Logic Programming
     
        (CLP) A programming framework based (like {Prolog}) on {LUSH}
        (or {SLD}) {resolution}, but in which {unification} has been
        replaced by a {constraint solver}.  A CLP {interpreter}
        contains a Prolog-like {inference engine} and an {incremental
        constraint solver}.  The engine sends constraints to the
        solver one at a time.  If the new constraint is consistent
        with the collected constraints it will be added to the set.
        If it was inconsistent, it will cause the engine to
        {backtrack}.
     
        {CLP*} is a variant.
     
        ["Constraint Logic Programming", J. Jaffar et al, 14th POPL,
        ACM 1987].
     
        (1994-11-01)