▁Oper ator ▁theory ▁ ▁P is ier ▁transformed ▁the ▁area ▁of ▁operator ▁spaces . ▁In ▁the ▁ 1 9 9 0 s , ▁he ▁solved ▁two ▁long - standing ▁open ▁problems . ▁In ▁the ▁theory ▁of ▁C * - al gebras , ▁he ▁solved , ▁joint ly ▁with ▁Mar ius ▁Jun ge , ▁the ▁problem ▁of ▁the ▁uniqu eness ▁of ▁C *   - norm s ▁on ▁the ▁tensor ▁product ▁of ▁two ▁copies ▁of   B ( H ), ▁the ▁bounded ▁linear ▁operators ▁on ▁a ▁Hil bert ▁space   H . ▁He ▁and ▁Jun ge ▁were ▁able ▁to ▁produce ▁two ▁such ▁tensor ▁norm s ▁that ▁are ▁none qu ivalent . ▁In   1 9 9 7 , ▁he ▁constructed ▁an ▁operator ▁that ▁was ▁polynomial ly ▁bounded ▁but ▁not ▁similar ▁to ▁a ▁contra ction , ▁answering ▁a ▁famous ▁question ▁of ▁Paul ▁Hal mos . ▁ ▁Awards ▁He ▁was ▁an ▁invited ▁speaker ▁at ▁the ▁ 1 9 8 3 ▁IC M ▁and ▁ ▁a ▁pl en ary ▁speaker ▁at ▁the ▁ 1 9 9 8 ▁IC M . ▁In ▁ 1 9 9 7 , ▁P is ier ▁received ▁the ▁Ost row ski ▁Prize ▁for ▁this ▁work . ▁He ▁is ▁also ▁a ▁recip ient ▁of ▁the ▁Gr ands ▁Prix ▁de ▁l ' Ac adémie ▁des ▁Sciences ▁de ▁Paris ▁in ▁ 1 9 9 2 ▁and ▁the ▁S alem ▁Prize ▁in ▁ 1 9 7 9 . ▁In ▁ 2 0 1 2 ▁he ▁became ▁a ▁fellow ▁of ▁the ▁American ▁Mathemat ical ▁Society . ▁ ▁Books