reserve R for Ring,
  I for Ideal of R,
  a, b for Element of R;
reserve R for add-associative right_zeroed right_complementable Abelian
    distributive left_unital non empty doubleLoopStr;
reserve I for Ideal of R;
reserve a,b for Element of R;
reserve x, y for Element of R/I;

theorem
  for R being commutative Ring, I being Ideal of R holds
  I is maximal iff R/I is Skew-Field by Th16,Th19,Th20;
