fact: Definition ax_ext' := ∀ ∀ sub' $1 $0 ~> sub' $0 $1 ~> $1 ≡' $0.
imports: Undecidability.FOL.Util.Syntax Undecidability.FOL.Util.sig_bin Undecidability.FOL.Util.FullTarski Undecidability.FOL.Util.FullDeduction List