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pl:prolog:pllib:proof_explanation [2019/06/27 15:50] (aktualna)
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 +====== Proof explanation ======
 +{{tag>​proof operators}}
 +===== Description =====
 +Explaining a proof
 +
 +**Source**: ​ The Art of Prolog
 +===== Download =====
 +Program source code: {{proof_explanation.pl}}
 +===== Listing =====
 +<code prolog>
 +/*
 +    explain(Goal) ​ :-
 +       ​Explains how the goal Goal was proved.
 +*/
 +    explain(Goal) :-  monitor(Goal,​Proof),​ interpret(Proof).
 +
 +:- op(40,​xfy,&​).
 +:- op(30,​xf,​is_true).
 +:- op(40,​xfy,​because).
 +:- op(40,​xfy,​with).
 +
 +%    monitor(Goal,​Proof) ​  See Program 17.21.
 +
 +    interpret(ProofA&​ProofB) :-
 +       ​interpret(ProofA),​ interpret(ProofB).
 +    interpret(failed(A,​Branches)) :-
 +       nl, writeln([A,'​ has failed with the following failure branches:'​]),​
 +       ​interpret(Branches).
 +    interpret([Fail|Fails]) :-
 +       ​interpret(Fail),​ nl, write('​NEW BRANCH'​),​ nl,
 +       ​interpret(Fails).
 +    interpret([ ]).
 +    interpret(fact(A)) :-
 +       nl, writeln([A,'​ is a fact in the database.'​]).
 +    interpret(A because B with Proof) :-
 +       nl, writeln([A,'​ is proved using the rule'​]),​
 +       ​display_rule(rule(A,​B)),​ interpret(Proof).
 +    interpret(no_match(A)) :-
 +       nl, writeln([A,'​ has no matching fact or rule in the rule base.'​]).
 +    interpret(unsearched) :-
 +       nl, writeln(['​The rest of the conjunct is unsearched.'​]).
 +
 +    display_rule(rule(A,​B)) :-
 +       ​write('​IF '), write_conjunction(B),​ writeln(['​THEN ',A ]).
 +
 +    write_conjunction(A&​B) :-
 +       ​write_conjunction(A),​ write('​ AND '),
 +       ​write_conjunction(B).
 +
 +    write_conjunction(A is_true) :-  write(A).
 +
 +     ​writeln([X|Xs]) :- write(X), writeln(Xs).
 +     ​writeln([]) :- nl.
 +
 +%    Program 17.22: Explaining a proof
 +</​code>​
 +===== Comments =====
  
pl/prolog/pllib/proof_explanation.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)
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