
theorem Th55:
  for x,y,z being set holds InnerVertices GFA1AdderStr(x,y,z) = {[
  <*x,y*>,xor2c]} \/ {GFA1AdderOutput(x,y,z)}
proof
  let x,y,z be set;
  set f = xor2c;
  set xy = [<*x,y*>,f];
  set S = GFA1AdderStr(x,y,z);
  thus InnerVertices S = {xy, GFA1AdderOutput(x,y,z)} by FACIRC_1:56
    .= {xy} \/ {GFA1AdderOutput(x,y,z)} by ENUMSET1:1;
end;
