proposition: Lemma combinations_bound (B : BSRS) n k l : n > 3 + l -> n > 4 + k -> bounded n (combinations B $k $l).
proof: Proof. revert n k l. induction B as [|[s t] B IH]; cbn; intros n k l H1 H2; solve_bounds. apply IH; lia. all: apply prep_string_bound; solve_bounds. Qed.
imports: Undecidability.FOL.Syntax.Facts Undecidability.FOL.Semantics.Tarski.FullFacts Undecidability.FOL.FST Undecidability.FOL.Sets.FST Lia Undecidability.PCP(PCP Util.PCP_facts Reductions.PCPb_iff_dPCPb) Undecidability(Shared.ListAutomation)