▁line . ▁With ▁K arel ▁P rik ry , ▁he ▁introduced ▁the ▁notion ▁of ▁precip it ous ▁ideal . ▁He ▁gave ▁several ▁models ▁where ▁the ▁ax iom ▁of ▁choice ▁failed , ▁for ▁example ▁one ▁with ▁ ω 1 ▁meas urable . ▁The ▁concept ▁of ▁a ▁Je ch – K un en ▁tree ▁is ▁named ▁after ▁him ▁and ▁Kenneth ▁Kun en . ▁ ▁Bibli ography ▁▁ ▁L ect ures ▁in ▁set ▁theory , ▁with ▁particular ▁emphas is ▁on ▁the ▁method ▁of ▁forcing , ▁Springer - Verlag ▁L ect ure ▁Notes ▁in ▁Mathemat ics ▁ 2 1 7 ▁( 1 9 7 1 ) ▁() ▁▁ ▁The ▁ax iom ▁of ▁choice , ▁North - Hol land ▁ 1 9 7 3 ▁( D over ▁paper back ▁edition ▁) ▁ ▁( with ▁K . ▁H rb á č ek ) ▁Introduction ▁to ▁set ▁theory , ▁Marcel ▁De k ker , ▁ 3 rd ▁edition ▁ 1 9 9 9 ▁() ▁ ▁Multiple ▁forcing , ▁Cambridge ▁University ▁Press ▁ 1 9 8 6 ▁() ▁ ▁Set ▁Theory : ▁The ▁Third ▁Mill en ni um ▁Edition , ▁re vised ▁and ▁expanded , ▁ 2 0 0 6 , ▁Springer ▁Science ▁& ▁Business ▁Media , ▁. ▁ 1 st ▁ed . ▁ 1 9 7 8 ; ▁ 2 nd ▁( correct ed ) ▁ed . ▁ 1 9 9 7 ▁ ▁References ▁ ▁External ▁links ▁ ▁Home ▁page , ▁with ▁a ▁copy ▁at ▁P enn ▁state . ▁ ▁Category : 1 9 4 4 ▁birth s ▁Category :