Direct Reflections
نویسندگان
چکیده
A pointed endofunctor (and in particular a reflector) (R, r) in a category X is direct iff for each morphism f : X→ Y the pullback of Rf against rY exists and the unique fill-in morphism u from X to the pullback is such that Ru is an isomorphism. (This is close to the concept of a simple reflector introduced by Cassidy, Hébert and Kelly in 1985.) We give sufficient conditions for directness, and for directness to imply reflectivity. We also relate directness to perfect morphisms, and we give several examples and counterexamples in general topology. Mathematics Subject Classifications (2000): 18A20, 18A40, 54C10, 54E15.
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ورودعنوان ژورنال:
- Applied Categorical Structures
دوره 8 شماره
صفحات -
تاریخ انتشار 2000