% SWI-Prolog/issues/issues/112
?- A=[B|_], C=[_|_], dif(C, A), C=[B|B].
   false, unexpected.

% scryer-prolog/issues/1455
?- A=[C|B], A=[B|A], C=[a|_], A=[C|B].
   false.
?-          A=[B|A], C=[a|_], A=[C|B].
   A = [[a|_A]|A], B = [a|_A], C = [a|_A], unexpected.

% scryer-prolog/issues/1434
?-                  R_0 = (A=[_|A],B=[D|D],G_0), G_0 = (A=[a|B]), R_0.
   false. % expected
?- G_0 = (A=[a|B]), R_0 = (A=[_|A],B=[D|D],G_0), G_0 = (A=[a|B]), R_0.
   G_0 = ([a|A]=[a,a|a]), A = [a|A], B = [a|a], R_0 = ([a|A]=[a|A],[a|a]=[a|a],[a|A]=[a,a|a]), D = a. % unexpected ; a specialization cannot lead to success of an already failing goal

% SWI-Prolog/issues/issues/109
?- D = [], A=[B|A], C=[D|B], dif(A, C), A=[D|A].
   D = B, B = [], A = [[]|A], C = [[]].
?-         A=[B|A], C=[D|B], dif(A, C), A=[D|A]. % generalization
   false, unexpected.

% SWI-Prolog/issues/issues/105
?- dif(A-C,B-D), C-D=z-z.
   false, unexpected.
?- dif(A-C,B-D), C-D=z-z.
   C = z, D = z, dif(A-z,B-z).
?- dif(A,[_|B]),A=[[]|_],A=[B].
   false, unexpected.
?- dif(A,[_|B]),A=[[]|_],A=[B].
   A = [[]], B = [].

% SWI-Prolog/issues/issues/15
?- dif(X-Y,1-2),X=Y, Y = 1.
   false, unexpected.
?- dif(X-Y,1-2),X=Y, Y = 1.
   X = 1, Y = 1.
?- dif(X-Y, 1-2), X = Y, X = 2.
   false, unexpected.
?- dif(X-Y, 1-2), X = Y.
   X = Y.
?- dif(X-Y, 1-2), X = Y.
   X = Y, dif(f(Y, Y), f(1, 2)), unexpected.