Intro rule for “∀r>0” in Isabelle
问题 When I have a goal such as "∀x. P x" in Isabelle, I know that I can write show "∀x. P x" proof (rule allI) However, when the goal is "∀x>0. P x" , I cannot do that. Is there a similar rule/method that I can use after proof in order to simplify my goal? I would also be interested in one for the situation where you have a goal of the form "∃x>0. P x" . I'm looking for an Isar proof that uses the proof (rule something) style. 回答1: Universal quantifier To expand on Lars's answer: ∀x>0. P x is