reserve i,j,k,n,m for Nat,
        X for set,
        b,s for bag of X,
        x for object;
reserve O for Ordinal,
        R for right_zeroed add-associative right_complementable
          right_unital distributive non trivial doubleLoopStr,
        p for Polynomial of O, R;

theorem
  support Subst(b,x,s) = support b\{x} \/ support s
proof
  support Subst(b,x,s) = support (b+*(x,0)) \/ support s by PRE_POLY:38;
  hence thesis by Th16;
end;
