“…Their complexity, however, seemed unacceptable, and was partially a motivation for the development of Flat Concurrent Prolog and the simpler non-flat languages, GHC, PARLOG, and CP(I,L), An abstract machine for PARLOG was developed by Gregory et al [68], and later optimized by Crammond [34). Another abstract machine for GHC was derived from the FCP machine by Levy [114]. Another abstract machine for GHC was derived from the FCP machine by Levy [114].…”