Startpunkten

Free_In_and_Rename_Var/lab2.pl

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+/*****************************/
+/* Christian Ohlsson         */
+/* Logik för dataloger       */
+/* Karlstad 990228           */
+/* Laboration 2 i Logik      */
+/*****************************/
+/* Functions included        */
+/* free_in                   */
+/* rename_var                */
+/*****************************/
+
+:- op(200, fx, -).
+:- op(400, xfy, #).
+:- op(400, xfy, &).
+:- op(700, xfy, ->).
+:- op(700, xfy, <->).
+
+exist(X, [H|T]) :- X = H, !, fail.
+exist(X, [H|T]) :- Z =.. T, free_in(X, Z).
+
+all(X, [H|T]) :- X = H, !, fail.
+all(X, [H|T]) :- Z =.. T, free_in(X, Z).
+
+operators(X, [H|T]) :- free_in(X, H), Z =.. T, free_in(X, Z).
+falsum(X) :- true.
+
+/* Del 1 - free_in */
+/* free_in(+variabel, +TermOrFormula */
+free_in(X, Y) :- Y =.. [H|T], T = [].
+
+free_in(X, Y) :- Y =.. [H|T], member(H, [&, #, ->, <->]), operators(X, T).
+free_in(X, Y) :- Y =.. [H|T], member(H, [all, exist]), call(H, X, T).
+free_in(X, Y) :- Y =.. [H|T], member(H, [-]), falsum(X).
+free_in(X, Y) :- Y =.. [H|T], member(H, [as, pr, fu, qu, rt]).
+
+/* Del 2 - rename_var  */
+/* rename_var(+Element, +TermOrFormula, +Nyttelement, -NyTermOrFormula) */
+ersatt(E1, E2, [], []).
+ersatt(E1, E2, [E1|R], [E2|S]) :- ersatt(E1, E2, R, S).
+ersatt(E1, E2, [X|R], [X|S]) :- ersatt(E1, E2, R, S).
+
+
+rv(E1, E2, [H|T], New) :- T = [], atom(H), ersatt(E1, E2, [H], New).
+rv(E1, E2, [H|T], New) :- T = [], rename_var(E1, H, E2, Next), append([Next], [], New).
+rv(E1, E2, [H|T], New) :- rv(E1, E2, T, N1), rv(E1, E2, [H], N2), append(N2,N1, New).
+rename_var(E1, Old, E2, New) :- Old =.. [H|T], T = [], ersatt(E1, E2, [H], Z), New =.. Z. 
+rename_var(E1, Old, E2, New) :- Old =.. [H|T], rv(E1, E2, T, Next), New =.. [H|Next].