fact: Definition encode_word_pair '(x, y) := encode_pair (encode_list encode_bool x) (encode_list encode_bool y).
imports: List Lia ssreflect ssrbool ssrfun Undecidability.HilbertCalculi.HSC Undecidability.HilbertCalculi.Util.HSCFacts Undecidability.PCP.PCP