theorem Th58:
  for G being Circuit-like non void non empty ManySortedSign
  for C being non-empty Circuit of G st X, A specifies C
  holds C calculates X, A
proof
  let G be Circuit-like non void non empty ManySortedSign;
  let C be non-empty Circuit of G;
  given f, g being Function such that
A1: C, X-Circuit A are_similar_wrt f, g;
  take f", g";
  thus f", g" form_embedding_of X-Circuit A, C by A1;
  X-Circuit A, C are_similar_wrt f", g" by A1,Th39;
  hence thesis by Th53;
end;
