A Lingua Franca for Concurrent Logic Programming

This paper describes such a lingua franca. 2. GHC and Parlog A GHC or Parlog program is a set of relations {R 1 , ... , R n }. Each R i is made up of guarded Horn clauses of the same name and arity. In Edinburgh Prolog syntax where H, G 1 , ... G m , B 1 , ... B n are atomic formulae (unitary Prolog goals) and m ³³ 1 and n ³³ 1 each clause has the following form H :- G 1 and ... and G m | B 1 and ... and B n The clause's head H gives its relation name and arity, and the G i s and B j s are its guard and body goals, separated by the commitment operator |. The meta-symbol and signifies a conjunction operator. The primitive true, which always succeeds, fills empty guards or bodies. The clause's declarative reading is H is true if G 1 and ... and G m and B 1 and ... and B n are true and is a place filler in GHC for the parallel conjunction operator ",", and in Parlog for either the parallel "," or the sequential conjunction operator "&". One or more clauses form an ordered relation C 1 or ... or C n . where each C i is a guarded Horn clause, or is a meta-symbol acting as a place filler for a clause search operator, and the symbol "." terminates the relation. In GHC or only stands for the parallel search operator "." whereas in Parlog i