2 00 2 Obstruction Theory in Model Categories
نویسنده
چکیده
Working in an arbitrary pointed proper model category, we define what it means for a cofibration to have an obstruction theory. We describe the cofibrations that have an obstruction theory with respect to all fibrations. Up to weak equivalence, retract, and cobase change, they are the cofibrations with weakly contractible target. Equivalently, they are the retracts of principal cofibrations. Without properness, the same classification holds for cofibrations with cofibrant source.
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