fact: Definition ax_eq_elem' := ∀ ∀ ∀ ∀ $3 ≡' $1 ~> $2 ≡' $0 ~> $3 ∈' $2 ~> $1 ∈' $0.
imports: Undecidability.FOL.Util.Syntax Undecidability.FOL.Util.sig_bin Undecidability.FOL.Util.FullTarski Undecidability.FOL.Util.FullDeduction List