Browsing by Author "Randal-Williams, Oscar"
Now showing items 1-10 of 10
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Abelian quotients of mapping class groups of highly connected manifolds
Galatius, Søren; Randal-Williams, Oscar (SpringerMathematische Annalen, 2015-10-12)We compute the abelianisations of the mapping class groups of the manifolds W²ⁿ_g = g(Sⁿ × Sⁿ) for n ≥ 3 and g ≥ 5. The answer is a direct sum of two parts. The first part arises from the action of the mapping class group ...
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An upper bound for the pseudoisotopy stable range
Randal-Williams, Oscar (SpringerMathematische Annalen, 2017-08-01)We prove that the pseudoisotopy stable range for manifolds of dimension 2n can be no better than (2n - 2). In order to do so, we define new characteristic classes for block bundles, extending our earlier work with Ebert, ...
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Cohomology of automorphism groups of free groups with twisted coefficients
Randal-Williams, OscarWe compute the groups H*(Aut(F$_{n}$);M) and H*(Out(F$_{n}$);M) in a stable range, where M is obtained by applying a Schur functor to H$_{Q}$ or H$_{Q}$, respectively the first rational homology and cohomology of F$_{n}$. ...
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Homological stability for automorphism groups
Randal-Williams, Oscar; Wahl, N (Academic PressAdvances in Mathematics, 2017-10-01)Given a family of groups admitting a braided monoidal structure (satisfying mild assumptions) we construct a family of spaces on which the groups act and whose connectivity yields, via a classical argument of Quillen, ...
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Homological stability for moduli spaces of high dimensional manifolds. I
Galatius, S; Randal-Williams, OscarWe prove a homological stability theorem for moduli spaces of simply connected manifolds of dimension 2n > 4, with respect to forming connected sum with S$^{n}$ x S$^{n}$ . This is analogous to Harer's stability theorem ...
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Homological stability for moduli spaces of high dimensional manifolds. II
Galatius, S; Randal-Williams, OscarWe prove a homological stability theorem for moduli spaces of manifolds of dimension 2$\textit{n}$, for attaching handles of index at least $\textit{n}$, after these manifolds have been stabilised by countably many copies ...
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Homological stability for spaces of embedded surfaces
Morán, FC; Randal-Williams, Oscar (Mathematical Sciences PublisherGeometry and Topology, 2017-05-10)© 2017, Mathematical Sciences Publishers. All rights reserved.We study the space of oriented genus-g subsurfaces of a fixed manifold M and, in particular, its homological properties. We construct a “scanning map” which ...
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Homological Stability for Spaces of Embedded Surfaces
Moran, Federico Cantero; Randal-Williams, Oscar (Mathematical Sciences PublisherGeometry & Topology, 2016)We study the space of oriented genus $\textit{g}$ subsurfaces of a fixed manifold $\textit{M}$, and in particular its homological properties. We construct a “scanning map” which compares this space to the space of sections ...
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Infinite loop spaces and positive scalar curvature
Botvinnik, B; Ebert, J; Randal-Williams, Oscar (SpringerInventiones Mathematicae, 2017-09-01)We study the homotopy type of the space of metrics of positive scalar curvature on high-dimensional compact spin manifolds. Hitchin used the fact that there are no harmonic spinors on a manifold with positive scalar curvature ...
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Tautological rings for high-dimensional manifolds
Galatius, S; Grigoriev, I; Randal-Williams, Oscar (Cambridge University PressCompositio Mathematica, 2017-04)We study tautological rings for high-dimensional manifolds, that is, for each smooth manifold $M$ the ring $R^*$($M$) of those characteristic classes of smooth fibre bundles with fibre $M$ which is generated by generalised ...