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 Th21:
  for x being FinSequence of K holds |(0*(K,len x),x)| = 0.K
proof
  let x be FinSequence of K;
  thus |(0*(K,len x),x)| = |(x,0*(K,len x))| by FVSUM_1:90
    .= 0.K by Th20;
end;
