proposition: Lemma vec_inv2 X (v : vec X 2) : v = Vector.cons (Vector.hd v) (Vector.cons (Vector.hd (Vector.tl v)) Vector.nil).
proof: Proof. apply (Vector.caseS' v). intros x w. apply (Vector.caseS' w). intros ?. now apply Vector.case0. Qed.
imports: Undecidability.FOL.Syntax.Facts Undecidability.FOL.Syntax.Asimpl Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.Deduction.FullNDFacts Undecidability.FOL.Sets(binZF ZF) Undecidability.FOL.Reductions.PCPb_to_ZF Undecidability(Shared.ListAutomation) Morphisms