Results 11 to 20 of about 74 (59)
The ∞$\infty$‐categorical reflection theorem and applications
Journal of Topology, Volume 19, Issue 1, March 2026.Abstract We prove an ∞$\infty$‐categorical version of the reflection theorem of AdÁmek and Rosický [Arch. Math. 25 (1989), no. 1, 89–94]. Namely, that a full subcategory of a presentable ∞$\infty$‐category that is closed under limits and κ$\kappa$‐filtered colimits is a presentable ∞$\infty$‐category.
Shaul Ragimov, Tomer M. Schlank
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Scissors congruence K$K$‐theory for equivariant manifolds
Bulletin of the London Mathematical Society, Volume 58, Issue 1, January 2026.Abstract We introduce a scissors congruence K$K$‐theory spectrum that lifts the equivariant scissors congruence groups for compact G$G$‐manifolds with boundary, and we show that on π0$\pi _0$, this is the source of a spectrum‐level lift of the Burnside ring‐valued equivariant Euler characteristic of a compact G$G$‐manifold.
Mona Merling +4 more
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On Fico's Lemmata and the homotopy type of certain gyrations
Bulletin of the London Mathematical Society, Volume 58, Issue 1, January 2026.Abstract We undertake to determine the homotopy type of gyrations of sphere products and of connected sums, thereby generalising results known in earlier literature as ‘Fico's Lemmata’ which underpin gyrations in their original formulation from geometric topology.
Sebastian Chenery
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Modeling (∞,1)$(\infty,1)$‐categories with Segal spaces
Bulletin of the London Mathematical Society, Volume 58, Issue 1, January 2026.Abstract In this paper, we construct a model structure for (∞,1)$(\infty,1)$‐categories on the category of simplicial spaces, whose fibrant objects are the Segal spaces. In particular, we show that it is Quillen equivalent to the models of (∞,1)$(\infty,1)$‐categories given by complete Segal spaces and Segal categories.
Lyne Moser, Joost Nuiten
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Combination of open covers with π1$\pi _1$‐constraints
Bulletin of the London Mathematical Society, Volume 57, Issue 12, Page 3886-3901, December 2025.Abstract Let G$G$ be a group and let F$\mathcal {F}$ be a family of subgroups of G$G$. The generalised Lusternik–Schnirelmann category catF(G)$\operatorname{cat}_\mathcal {F}(G)$ is the minimal cardinality of covers of BG$BG$ by open subsets with fundamental group in F$\mathcal {F}$.
Pietro Capovilla, Kevin Li, Clara Löh
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Model category structures on truncated multicomplexes for complex geometry
Bulletin of the London Mathematical Society, Volume 57, Issue 12, Page 4163-4177, December 2025.Abstract To a bicomplex one can associate two natural filtrations, the column and row filtrations, and then two associated spectral sequences. This can be generalized to N$N$‐multicomplexes. We present a family of model category structures on the category of N$N$‐multicomplexes where the weak equivalences are the morphisms inducing a quasi‐isomorphism ...
Joana Cirici +2 more
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Hom ω$\omega$‐categories of a computad are free
Journal of the London Mathematical Society, Volume 112, Issue 6, December 2025.Abstract We provide a new description of the hom functor on weak ω$\omega$‐categories, and show that it admits a left adjoint that we call the suspension functor. We then show that the hom functor preserves the property of being free on a computad, in contrast to the hom functor for strict ω$\omega$‐categories.
Thibaut Benjamin, Ioannis Markakis
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The flat cover conjecture for monoid acts
Journal of the London Mathematical Society, Volume 112, Issue 6, December 2025.Abstract We prove that the Flat Cover Conjecture holds for the category of (right) acts over any right‐reversible monoid S$S$, provided that the flat S$S$‐acts are closed under stable Rees extensions. The argument shows that the class F$\mathcal {F}$‐Mono (S$S$‐act monomorphisms with flat Rees quotient) is cofibrantly generated in such categories ...
Sean Cox
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Real models for the framed little n$n$‐disks operads
Journal of Topology, Volume 18, Issue 4, December 2025.Abstract We study the action of the orthogonal group on the little n$n$‐disks operads. As an application we provide small models (over the reals) for the framed little n$n$‐disks operads. It follows in particular that the framed little n$n$‐disks operads are formal (over the reals) for n$n$ even and coformal for all n$n$.
Anton Khoroshkin, Thomas Willwacher
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Parametrized stability and the universal property of global spectra
Journal of Topology, Volume 18, Issue 4, December 2025.Abstract We develop a framework of parametrized semiadditivity and stability with respect to so‐called atomic orbital subcategories of an indexing ∞$\infty$‐category T$T$, extending work of Nardin. Specializing this framework, we introduce global ∞$\infty$‐categories and the notions of equivariant semiadditivity and stability, yielding a higher ...
Bastiaan Cnossen +2 more
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