reserve D for non empty set,
  i,j,k,l for Nat,
  n for Nat,
  x for set,
  a,b,c,r,r1,r2 for Real,
  p,q for FinSequence of REAL,
  MR,MR1 for Matrix of REAL;

theorem
  for M being Matrix of REAL st M = {} holds SumAll M = 0
proof
  let M be Matrix of REAL;
  assume M = {};
  then reconsider M1=M as Matrix of 0,width M,REAL by MATRIX_0:13;
  len M1 = 0 by MATRIX_0:22;
  hence thesis by MATRPROB:23;
end;
