
theorem
  for M1,M2 being Matrix of COMPLEX st width M1=len M2 &len M1>0&len M2>
  0 holds 0_Cx(len M1,width M1)*M2=0_Cx(len M1,width M2)
proof
  let M1,M2 be Matrix of COMPLEX;
A1: len M1=len COMPLEX2Field M1;
  assume width M1=len M2 & len M1>0 & len M2>0;
  hence thesis by A1,Th22;
end;
