= {x* E X*/(j(X*),Xi)< ai,i = 1,2,...,n} = {x* E X*/(X*,Xi)< ai,i = 1,2,...,n}.
Vi f la anh X1;Llien tl.lC tren cac khang gian con hUll h1;Lnchi~u ~clla X nen
1M : K n M -t X* lien t\lC yell tren X. Do do fi/(j-l(Uxi,aJ), i = 1,2, ...,n la t~p ma
trong K n M. Vi K la t~p dong, giOi[r]