 reserve x,y,X,Y for set;
reserve G for non empty multMagma,
  D for set,
  a,b,c,r,l for Element of G;
reserve M for non empty multLoopStr;
reserve H for non empty SubStr of G,
  N for non empty MonoidalSubStr of G;

theorem
  for F being non empty SubStr of D*+^ st {} is Element of F holds
  F is unital & the_unity_wrt the multF of F = {}
proof
  let F be non empty SubStr of D*+^;
  the_unity_wrt op(D*+^) = {} by Th60;
  hence thesis by Th30;
end;
