37 lines
681 B
Prolog
37 lines
681 B
Prolog
:- use_module(library(chr)).
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handler modelgenerator.
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constraints attends/3, requires/2, less/2, leq/2.
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operator(700,xfx,less).
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operator(700,xfx,leq).
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X less Y <=> nonvar(X), nonvar(Y) | X < Y.
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X less Y \ X less Z <=> Y =< Z | true.
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X less Y, X leq Y <=> false.
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X leq X <=> true.
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attends(S, Y, TY), requires(Y, X) ==> attends(S, X, TX), TX less TY.
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attends(john,C,T) ==> true | (T leq 1996 ; T less 1994).
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example :-
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attends(john,constraintprogrammierung,1996),
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requires(constraintprogrammierung,logik).
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/*
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?- example.
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requires(constraintprogrammierung,logik),
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_A less 1994,
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attends(john,constraintprogrammierung,1996),
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attends(john,logik,_A) ?
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*/
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