reserve E, x, y, X for set;
reserve A, B, C, D for Subset of E^omega;
reserve a, a1, a2, b, c, c1, c2, d, ab, bc for Element of E^omega;
reserve e for Element of E;
reserve i, j, k, l, n, n1, n2, m for Nat;

theorem Th2:
  n1 + n <= n2 + 1 & n > 0 implies n1 <= n2
proof
  assume that
A1: n1 + n <= n2 + 1 and
A2: n > 0;
  1 + 0 <= n by A2,NAT_1:13;
  hence thesis by A1,XREAL_1:8;
end;
