The Free On-line Dictionary of Computing (30 December 2018):

ABSYS

    An early declarative language from the
   University of Aberdeen which anticipated a number of
   features of Prolog.

   ["ABSYS: An Incremental Compiler for Assertions", J.M. Foster
   et al, Mach Intell 4, Edinburgh U Press, 1969, pp. 423-429].

   (1994-11-08)