, ▁inspired ▁by ▁many ▁of ▁the ▁world ▁leaders ▁in ▁this ▁field , ▁including ▁Stephen ▁S male ▁and ▁René ▁Thom , ▁who ▁both ▁spent ▁time ▁at ▁War wick . ▁Ze eman ▁subsequently ▁spent ▁a ▁s abb at ical ▁with ▁Thom ▁at ▁the ▁Institut ▁des ▁Haut es ▁Ét udes ▁Scient if iques ▁in ▁Paris , ▁where ▁he ▁became ▁interested ▁in ▁cat ast rop he ▁theory . ▁On ▁his ▁return ▁to ▁War wick , ▁he ▁taught ▁an ▁under grad uate ▁course ▁in ▁Cat ast rop he ▁Theory ▁that ▁became ▁imm ens ely ▁popular ▁with ▁students ; ▁his ▁lect ures ▁generally ▁were ▁" standing ▁room ▁only ". ▁In ▁ 1 9 7 3 ▁he ▁gave ▁an ▁M . Sc . ▁course ▁at ▁War wick ▁giving ▁a ▁complete ▁detailed ▁proof ▁of ▁Thom ' s ▁classification ▁of ▁elementary ▁cat ast roph es , ▁mainly ▁following ▁an ▁un pub lished ▁manuscript , ▁" Right - equ ival ence " ▁written ▁by ▁John ▁M ather ▁at ▁War wick ▁in ▁ 1 9 6 9 . ▁David ▁T rot man ▁wrote ▁up ▁his ▁notes ▁of ▁the ▁course ▁as ▁an ▁M . Sc . ▁th esis . ▁These ▁were ▁then ▁distributed ▁in ▁thousands ▁of ▁copies ▁throughout ▁the ▁world ▁and ▁published ▁both ▁in ▁the ▁proceed ings ▁of ▁a ▁ 1 9 7 5 ▁Seattle ▁conference ▁on ▁cat ast rop he ▁theory ▁and ▁its ▁applications , ▁and ▁in ▁a ▁ 1 9 7 7 ▁collection ▁of ▁papers ▁on ▁cat ast rop he ▁theory ▁by ▁Ze eman . ▁In ▁ 1 9 7 4 ▁Ze eman