reserve N for Nat;
reserve n,m,n1,n2 for Nat;
reserve q,r,r1,r2 for Real;
reserve x,y for set;
reserve w,w1,w2,g,g1,g2 for Point of TOP-REAL N;
reserve seq,seq1,seq2,seq3,seq9 for Real_Sequence of N;

theorem Th11:
  -seq = (-1)*seq
proof
  let n be Element of NAT;
  thus ((-1)*seq).n=(-1)*seq.n by Th5
    .=-seq.n by RLVECT_1:16
    .=(-seq).n by Th6;
end;
