Isabelle: proof obligation - proving using counterexamples -


for example lemma this:

lemma somefunclemma: "∀ (e::sometype) . pre_somefunc 2 e"

which gives following when using quickcheck:

auto quickcheck found counterexample:   e = - 1

or when using nitpick (which isn't main point here):

nitpick found counterexample:    skolem constant:     e = - 1

how can use counterexample finish proof?

as can see, i'm not familiar isabelle , pos.

thank help!

the presence of counterexample indicates won't able prove proposition, except maybe

  • the counterexample spurious;

  • the underlying logic inconsistent.


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