reserve X for RealUnitarySpace;
reserve x, y, z, g, g1, g2 for Point of X;
reserve a, q, r for Real;
reserve seq, seq1, seq2, seq9 for sequence of X;
reserve k, n, m, m1, m2 for Nat;

theorem Th8:
  seq is convergent implies seq - x is convergent
proof
  assume seq is convergent;
  then seq + (-x) is convergent by Th7;
  hence thesis by BHSP_1:56;
end;
