--- pl:prolog:pllib:state-space [2019/06/27 15:50]
+++ pl:prolog:pllib:state-space [2019/06/27 15:50] (aktualna)
@@ Linia 1: / Linia 1: @@
+====== State-space ======
+{{tag>planning}}
+===== Description =====
+A state-space definition for means-ends planning based on goal regression.
+**Source**:  PROLOG programming for artificial intelligence, 3rd Edition, Harlow, 2001, ISBN 0-201-40375-7.
+===== Download =====
+Program source code: {{state-space.pl}}
+===== Listing =====
+<code prolog>
+% Figure 17.9  A state-space definition for means-ends planning based on goal
+% regression. Relations satisfied, achieves, preserves, regress, addnew and
+% delete_all are as defined in Figure 17.8.
+% State space representation of means-ends planning with goal regression
+:- op( 300, xfy, ->).
+s( Goals -> NextAction, NewGoals -> Action, 1)  :-   % All costs are 1
+  member( Goal, Goals),
+  achieves( Action, Goal),
+  can( Action, Condition),
+  preserves( Action, Goals),
+  regress( Goals, Action, NewGoals).
+goal( Goals -> Action) :-
+  start( State),                    % User-defined initial situation
+  satisfied( State, Goals).         % Goals true in initial situation
+h( Goals -> Action, H)  :-                   % Heuristic estimate
+  start( State),
+  delete_all( Goals, State, Unsatisfied),    % Unsatisfied goals
+  length( Unsatisfied, H).                   % Number of unsatisfied goals
+</code>
+===== Comments =====

pl/prolog/pllib/state-space.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)

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