我有一个文件，我用作定理证明器prover9的输入。它只包含假设。我决定使用其中一个假设作为目标来测试prover9。显然这应该被证明。
然而，我收到警告'拒绝共享常数'然后'搜索失败'。该文件如下所示
formulas(assumptions).
% this is the given data -------------------------------------------
parent(adam, jill). parent(eve, jill). parent(adam, bill). parent(eve, bill).
parent(ed, mary). parent(ann, mary). parent(ed, diana). parent(ann, diana).
parent(bill, cathy). parent(mary, cathy). parent(bill, jon). parent(mary, jon).
parent(phil, sue). parent(sheila, sue). parent(phil, ben). parent(sheila, ben).
parent(jim,beth). parent(cathy, beth). parent(jim, tony). parent(cathy, tony).
parent(jon, pat). parent(sue, pat). parent(dave, ruth). parent(liz, ruth).
parent(dave, vicky). parent(liz, vicky). parent(tony, ron). parent(ruth, ron).
parent(pat, harry). parent(ben, henry). parent(henry, helen).
male(adam). male(bill). male(ed). male(jon). male(phil). male(ben). male(pat).
male(jim). male(tony). male(harry). male(henry). male(dave). male(ron). male(sam).
female(eve). female(ann). female(jill). female(mary). female(vicky). female(helen).
female(diana). female(sheila). female(cathy). female(sue). female(beth). female(ruth).
female(liz). female(pat).
married(adam, eve). married(ed, ann). married(jill, sam). married(bill, mary).
married(phil, sheila). married(dave, liz). married(cathy, jim). married(jon, sue).
married(tony, ruth).
% ------------------------------------------------------------------
% This is the given grandparent definition
all X all Y ( grandparent(X,Y) <-> (exists Z (parent(X,Z) & parent(Z,Y))) ).
% -------------------------------------------------------------------
% this is the additional data for testing sister property
adam != eve. jill != bill. ed != ann. mary != diana.
sue != ben. mary != bill. jon != cathy. cathy != jim.
dave != liz. vicky != ruth. phil != sheila. tony != beth.
% --------------------------------------------------------------------
end_of_list.
set(prolog_style_variables).
formulas(goals).
parent(adam, jill).
end_of_list.