
theorem Lm65A1:
for V be RealNormSpace st V is non trivial holds
  DualSp V is non trivial
proof
   let V be RealNormSpace;
   assume V is non trivial; then
   consider F be Point of DualSp V such that
A1: ||.F.|| = 1 by Lm65A;
   F <> 0.(DualSp V) by A1;
   hence thesis;
end;
