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  1.  
  2. :- op(100, yfx, '@').
  3.  
  4. reduction(if @ A @ B @ C, Y) :- !,
  5.     reduction(A, X),
  6. 	(X == 0 ->
  7. 		reduction(C, Y) ;
  8. 		reduction(B, Y)).
  9.  
  10. reduction(A @ B, Y) :- !,
  11. 	reduction(A, P),
  12. 	reduction(B, Q),
  13. 	copy_term(P, z(Q, X)), reduction(X, Y).
  14.  
  15. reduction(z(X,Y), z(X,Y)) :- !.
  16.  
  17. reduction(A * B, C) :- !,
  18. 	reduction(A, A2),
  19. 	reduction(B, B2),
  20. 	C is A2 * B2.
  21.  
  22. reduction(A - B, C) :- !,
  23. 	reduction(A, A2),
  24. 	reduction(B, B2),
  25. 	C is A2 - B2.
  26.  
  27. reduction(X, X) :- integer(X), !.
  28. reduction(X, X) :- write('cannot reduction' :- X), nl, halt.
  29.  
  30. ?-
  31. 	Y = z(F, z(X, F @ z(V, X @ X @ V)) @ z(X, F @ z(V, X @ X @ V))),
  32. 	reduction(Y @ z(H, z(N, if @ N @ (H @ (N - 1) * N) @ 1)) @ 7, Result),
  33. 	write(Result), nl,
  34. 	halt.
  35.  
  36.  
Success #stdin #stdout 0.02s 6160KB
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https://ideone.com/ia35tL
language:
Prolog (swi 7.6.4)
created:
11 years ago
visibility:
public

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