An introduction to fibrations topos theory the effective topos and modest sets

Atoposisacategoricalmodelofconstructivesettheory.Inparticular,theeectivetoposisthe categorical'universe'ofrecursivemathematics.Amongitsobjectsarethemodestsets,which formaset-theoreticmodelforpolymorphism.Moreprecisely,thereisabrationofmodestsets whichsati