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1)How to choose assumption that I want to apply in Isabelle/FOL theorem?

There is a case of proof, where I cannot use "apply assumption".

 axiomatization
  where aax8  : ‹(A-->C)-->(B-->C)-->(A∨B-->C)›
    and aax11 : "A∨~A"

lemma ewfw : ‹ ⟦(A-->B); ~A-->B⟧==>B›
  apply(rule mp)
   apply(rule mp)
  apply(rule mp)
     apply(rule aax8)

    apply assumption
  ???
  done

I have a situation with such state of interactive proof:

proof (prove)
goal (2 subgoals):
 1. (A --> B) ==> (¬ A --> B) ==> (?B9 --> B)
 2. (A --> B) ==> (¬ A --> B) ==> (A ∨ ?B9)

Another way to solve this problem is to choose another goal.

2) How to choose goal that I want to prove next?

Another way is to replace variable with questionmark (?B9) with formula "~A", so

3) How can I specify metavariable with formula during the proof?

ged
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  • The proof state you are quoting does not seem to match the proof above, so I am confused. It may help to edit your question to contain the full theory. – Alex Krauss Sep 17 '19 at 08:12
  • Ad 2) You can use `prefer 2` to move the 2nd subgoal to the front. Such manipulations may be good for experimentation, but they general lead to unreadable proofs, so try to convert to Isar once you are done. – Alex Krauss Sep 17 '19 at 08:13

0 Answers0