reserve

  k,n,m,i,j for Element of NAT,
  K for Field;
reserve L for non empty addLoopStr;
reserve G for non empty multLoopStr;

theorem
  for A being Matrix of 0,K holds A is invertible
proof
  let A be Matrix of 0,K;
  A*A= 1.(K,0) by Th15;
  then A is_reverse_of A by MATRIX_6:def 2;
  hence thesis by MATRIX_6:def 3;
end;
