. A T ] 2 3 Se p 20 01 OBSTRUCTION THEORY IN MODEL CATEGORIES
نویسنده
چکیده
Working in an arbitrary pointed proper model category, 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.
منابع مشابه
Ju n 20 06 COMPARING HOMOTOPY CATEGORIES
Given a suitable functor T : C → D between model categories, we define a long exact sequence relating the homotopy groups of any X ∈ C with those of TX , and use this to describe an obstruction theory for lifting an object G ∈ D to C. Examples include finding spaces with given homology or homotopy groups.
متن کاملar X iv : h ep - l at / 0 10 90 34 v 1 2 8 Se p 20 01 1 Lattice Matter
I review recent developments in the study of strongly interacting field theories with non-zero chemical potential µ. In particular I focus on (a) the determination of the QCD critical endpoint in the (µ, T) plane; (b) superfluid condensates in Two Color QCD; and (c) Fermi surface effects in the NJL model. Some remarks are made concerning the relation of superconductivity with the sign problem.
متن کاملEffect of dietary selenium and vitamin E on the primary and secondary immune response in lambs challenged with parainfluenza3 virus.
This study was conducted to determine the effect of dietary selenium (Se) and vitamin E (Vit E) on various blood characteristics and the primary and secondary humoral immune response of lambs challenged with parainfluenza3 virus (PI3 V). Treatments included: 1) +Se/+Vit E, 2) -Se/+Vit E, 3) +Se/-Vit E and 4) -Se/-Vit E. The basal diet (-Se/-Vit E) was deficient in Se and Vit E. Sodium selenite ...
متن کاملStudies of standard liver function and hepatic fibrosis in rats with obstructive jaundice and biliary drainage.
ABSTRUCT The authors prepared the obstructive jaundice model on which the external biliary drainage was operable, and tried to clarify the critical duration of obstruction from the aspects of the standard liver function and hepatic fibrosis, and the following results were obtained. 1) The T. B, Al-p, GOT and GPT levels in 1 to 4 weeks after the common bile duct obstruction was significantly hig...
متن کاملSe p 20 06 Cofibrations in Homotopy Theory
We define Anderson-Brown-Cisinski (ABC) cofibration categories, and construct homotopy colimits of diagrams of objects in ABC cofibraction categories. Homotopy colimits for Quillen model categories are obtained as a particular case. We attach to each ABC cofibration category a right derivator. A dual theory is developed for homotopy limits in ABC fibration categories and for left derivators. Th...
متن کامل