▁of ▁Gö del ' s ▁second ▁in comple ten ess ▁theorem , ▁employ ing ▁only ▁words ▁of ▁one ▁sy ll able . ▁At ▁the ▁end ▁of ▁his ▁v iva , ▁Hil ary ▁Put nam ▁asked ▁him , ▁" And ▁tell ▁us , ▁Mr . ▁Bool os , ▁what ▁does ▁the ▁analyt ical ▁hierarchy ▁have ▁to ▁do ▁with ▁the ▁real ▁world ?" ▁Without ▁hes it ating ▁Bool os ▁replied , ▁" It ' s ▁part ▁of ▁it ". ▁ ▁An ▁expert ▁on ▁puzz les ▁of ▁all ▁kinds , ▁in ▁ 1 9 9 3 ▁Bool os ▁reached ▁the ▁London ▁Regional ▁Final ▁of ▁The ▁Times ▁cross word ▁competition . ▁His ▁score ▁was ▁one ▁of ▁the ▁highest ▁ever ▁recorded ▁by ▁an ▁American . ▁He ▁wrote ▁a ▁paper ▁on ▁" The ▁Hard est ▁Log ic ▁P uzz le ▁Ever " — one ▁of ▁many ▁puzz les ▁created ▁by ▁Raymond ▁Sm ul ly an . ▁ ▁Work ▁ ▁Bool os ▁co author ed ▁with ▁Richard ▁Jeff rey ▁the ▁first ▁three ▁ed itions ▁of ▁the ▁classic ▁university ▁text ▁on ▁mathematical ▁logic , ▁Comput ability ▁and ▁Log ic . ▁The ▁book ▁is ▁now ▁in ▁its ▁fifth ▁edition , ▁the ▁last ▁two ▁ed itions ▁updated ▁by ▁John ▁P . ▁Burg ess . ▁ ▁Kurt ▁Gö del ▁wrote ▁the ▁first ▁paper ▁on ▁prov ability ▁logic , ▁which ▁applies ▁modal ▁logic — the ▁logic ▁of ▁necessity ▁and ▁possibility — to ▁the ▁theory ▁of ▁mathematical ▁proof , ▁but ▁Gö del ▁never ▁developed ▁the ▁subject ▁to ▁any ▁significant ▁extent . ▁Bool os ▁was ▁one ▁of