fact: Definition is_power (x t : term') := ∀ $0 ∈' t`[↑] <~> sub' $0 x`[↑].
imports: Undecidability.FOL.Util.Syntax Undecidability.FOL.Util.sig_bin Undecidability.FOL.Util.FullTarski Undecidability.FOL.Util.FullDeduction List