reserve x for set,
  R for non empty Poset;
reserve S1 for OrderSortedSign,
  OU0 for OSAlgebra of S1;
reserve s,s1,s2,s3,s4 for SortSymbol of S1;

theorem Th6:
  Constants(OU0,s) c= OSConstants(OU0,s)
proof
  Constants(OU0,s) in {Constants(OU0,s2) : s2 <= s};
  hence thesis by ZFMISC_1:74;
end;
