Abstract

this paper a systematic study is made of various notions of "proper map" in the context of toposes. Modulo some separation conditions, a proper map Y ! X of spaces is generally understood to be a continuous function which preserves compactness of subspaces under inverse image, and which therefore in particular has compact fibers. In this spirit, a first definition of proper map between toposes was put forward by Johnstone in []. There, a map of toposes f : F ! E was called proper if f

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