نتایج جستجو برای: module contractible
تعداد نتایج: 67318 فیلتر نتایج به سال:
Examples are given to show that some compact contractible 4-manifolds can be knotted in the 4-sphere. It is then proved that any finitely presented perfect group is a knot group for an embedding of some contractible 4-manifold in S.
There are known infinite families of Brieskorn homology 3-spheres which can be realized as boundaries of smooth contractible 4-manifolds. In this paper we show that smooth free periodic actions on these Brieskorn spheres do not extend smoothly over a contractible 4-manifold. We give a new infinite family of examples in which the actions extend locally linearly but not smoothly.
We show that if K is a nilpotent finite complex, then ΩK can be built from spheres using fibrations and homotopy (inverse) limits. This is applied to show that if map∗(X,S ) is weakly contractible for all n, then map ∗ (X,K) is weakly contractible for any nilpotent finite complex K . AMS Classification numbers Primary: 55Q05 Secondary: 55P50
let $r$ be a right artinian ring or a perfect commutativering. let $m$ be a noncosingular self-generator $sum$-liftingmodule. then $m$ has a direct decomposition $m=oplus_{iin i} m_i$,where each $m_i$ is noetherian quasi-projective and eachendomorphism ring $end(m_i)$ is local.
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