reserve x for set,
  D for non empty set,
  k,n,m,i,j,l for Nat,
  K for Field;

theorem Th65:
  for n,m being Nat st n>0 holds 0_Rmatrix(n,m)+
  0_Rmatrix(n,m)=0_Rmatrix(n,m)
proof
  let n,m be Nat;
  assume
A1: n>0;
  then width (0_Rmatrix(n,m))=m & len (0_Rmatrix(n,m))=n by MATRIX_0:23;
  then (0+0) *(0_Rmatrix(n,m))=0_Rmatrix(n,m) by A1,MATRIXR1:44;
  hence thesis by Th12;
end;
