▁in ▁hom ological ▁algebra , ▁but ▁his ▁principal ▁research ▁area ▁for ▁a ▁number ▁of ▁years ▁has ▁been ▁category ▁theory . ▁ ▁He ▁is ▁well ▁known ▁to ▁theoretical ▁computer ▁scient ists ▁for ▁his ▁book ▁Category ▁Theory ▁for ▁Comput ing ▁Science ▁with ▁Charles ▁Well s , ▁as ▁well ▁as ▁for ▁the ▁development ▁of ▁* - aut onom ous ▁categories ▁and ▁Ch u ▁spaces ▁which ▁have ▁found ▁various ▁applications ▁in ▁computer ▁science . ▁ ▁His ▁mon ograph ▁* - aut onom ous ▁categories , ▁and ▁his ▁books ▁Top oses , ▁Tri ples , ▁and ▁The ories , ▁also ▁co author ed ▁with ▁Well s , ▁and ▁A cyc lic ▁Mod els , ▁are ▁aim ed ▁at ▁more ▁special ized ▁aud ien ces . ▁ ▁He ▁is ▁on ▁the ▁editor ial ▁bo ards ▁of ▁Mathemat ical ▁Struct ures ▁in ▁Computer ▁Science ▁and ▁the ▁electronic ▁journal ▁Hom ology , ▁Hom ot opy ▁and ▁App lications , ▁and ▁is ▁editor ▁of ▁the ▁electronic ▁journal ▁Theory ▁and ▁App lications ▁of ▁C ategories . ▁ ▁References ▁ ▁External ▁links ▁ ▁Top oses , ▁Tri ples ▁and ▁The ories , ▁updated ▁edition ▁of ▁text ▁published ▁in ▁ 1 9 8 3 . ▁ ▁Category ▁Theory ▁for ▁Comput ing ▁Science ▁updated ▁edition ▁of ▁text ▁published ▁in ▁ 1 9 9 9 . ▁▁ ▁http :// www . tac . m ta . ca / tac ▁( The ory ▁and ▁App lications ▁of ▁C ategories ) ▁ ▁https :// web . archive . org / web / 2 0 0 8 0 7 0