reserve i, j, m, n for Nat,
  z, B0 for set,
  f, x0 for real-valued FinSequence;

theorem Th27:
  1<=i & i<=n implies |. Base_FinSeq(n,i) .| = 1
proof
  assume that
A1: 1<=i and
A2: i<=n;
  sqrt Sum (Base_FinSeq(n,i))=1 by A1,A2,Th26,SQUARE_1:18;
  hence thesis by Th25;
end;
