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@Kuniwak
Last active August 28, 2021 00:33
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theorem
fixes f :: "'x ⇒ 'y ⇒ 'y"
assumes finite: "finite X"
and eq: "⋀x. x ∈ X ⟹ f x = g x"
shows "Finite_Set.fold f z X = Finite_Set.fold g z X"
using finite using eq by (rule_tac fold_closed_eq[where ?B=UNIV]; simp)
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