 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;

theorem Th16:
  M is well-unital iff
    for a being Element of M holds (1.M)*a = a & a*(1.M) = a;
