reserve x,y,z for object,
  i,j,n,m for Nat,
  D for non empty set,
  s,t for FinSequence,
  a,a1,a2,b1,b2,d for Element of D,
  p, p1,p2,q,r for FinSequence of D;
reserve M,M1,M2 for Matrix of D;
reserve f for FinSequence of D;
reserve i,j,i1,j1 for Nat;
reserve k for Nat, G for Matrix of D;

theorem
  for M1 being Matrix of 0, n, D, M2 being Matrix of 0, m, D holds M1 = M2
proof
  let M1 be Matrix of 0, n, D, M2 be Matrix of 0, m, D;
  len M1 = 0 & len M2 = 0 by Def2;
  hence thesis by CARD_2:64;
end;
