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

Extended Self-containing Prolog

    (ESP) An object-oriented extension of KL0 by
   Chikayama.  ESP has backtracking-based control,
   unification-based parameter passing and object-oriented
   calling.  An object in ESP is an axiom set.  A class
   definition consists of nature definitions (inheritance),
   slot definitions (class variables) and clause definitions.
   ESP has multiple inheritance similar to Flavors.  It has
   been implemented for ICOT's PSI Sequential Inference
   machine.

   See also CESP.

   E-mail: .

   ["Unique Features of ESP", T. Chikayama, Proc Intl Conf 5th
   Gen Comp Sys, ICOT 1984].

   (1994-12-08)