I was just browsing and noticed that the published proof of bianir has has two redundant commutations of logical equivalence. The shorter proof goes
1. bi2 .. ⊢ ((ψ ↔ φ) → (φ → ψ)) 2. impcom .1. ⊢ ((φ ∧ (ψ ↔ φ)) → ψ) Regards Roger -- You received this message because you are subscribed to the Google Groups "Metamath" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/metamath/0b4dceef-78a2-4560-a879-9576192d7a95o%40googlegroups.com.
