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Given a C*-algebra $A$, a discrete abelian group $X$ and a homomorphism $\Theta: X\to$ Out$A$ defining the dual action group $\Gamma\subset$ aut$A$, the paper contains results on existence and characterization of Hilbert $\{A,\Gamma\}$,…

Operator Algebras · Mathematics 2007-05-23 H. Baumgaertel , F. Lledo

We give a characterization of those Alexandrov spaces admitting a cohomogeneity one action of a compact connected Lie group $G$ for which the action is Cohen--Macaulay. This generalizes a similar result for manifolds to the singular setting…

Differential Geometry · Mathematics 2019-11-22 Manuel Amann , Masoumeh Zarei

In this article, we provide an exposition about symplectic toric manifolds, which are symplectic manifolds $(M^{2n}, \omega)$ equipped with an effective Hamiltonian $\mathbb{T}^n\cong (S^1)^n$-action. We summarize the construction of $M$ as…

Symplectic Geometry · Mathematics 2021-03-17 Haniya Azam , Catherine Cannizzo , Heather Lee

We classify which of the 672 oriented diffeomorphism types of closed, simply-connected spin 7-manifolds with the cohomology ring of $S^2\times S^5$ admit a free circle action. In addition, we show that whenever such an action exists, there…

Geometric Topology · Mathematics 2026-04-01 Philipp Reiser

This survey gives an overview of three central algebraic themes related to the study of splines: duality, group actions, and homology. Splines are piecewise polynomial functions of a prescribed order of smoothness on some subdivided domain…

Numerical Analysis · Mathematics 2023-12-18 Martina Lanini , Hal Schenck , Julianna Tymoczko

We explore various geometrical aspects of an action for six-dimensional chiral 2-forms based on the formalism of 1903.12196. We elucidate the coupling to general backgrounds and construct the full supersymmetric completion to an abelian…

High Energy Physics - Theory · Physics 2020-05-20 E. Andriolo , N. Lambert , C. Papageorgakis

In the past two decades, extensive research has been conducted on the (co)homology of various models of random simplicial complexes. So far, it has always been examined merely as a list of groups. This paper expands upon this by describing…

Algebraic Topology · Mathematics 2024-08-21 Jon V. Kogan

Using examples of a D=2 chiral scalar and a duality-symmetric formulation of D=4 Maxwell theory we study duality properties of actions for describing chiral bosons. In particular, in the D=4 case, upon performing a duality transform of an…

High Energy Physics - Theory · Physics 2009-10-31 Alexey Maznytsia , Christian Preitschopf , Dmitri Sorokin

We classify compact homogeneous geometries of irreducible spherical type and rank at least 2 which admit a transitive action of a compact connected group, up to equivariant 2-coverings. We apply our classification to polar actions on…

Group Theory · Mathematics 2014-04-17 Linus Kramer , Alexander Lytchak

We study the smooth untwisted cohomology with real coefficients for the action on [SL(2, R) \times \cdot \cdot \cdot \times SL(2, R)]/{\Gamma} by the subgroup of diagonal matrices, where {\Gamma} is an irreducible lattice. In the top…

Dynamical Systems · Mathematics 2013-12-17 Felipe A. Ramirez

Symmetric homology is an analog of cyclic homology in which the cyclic groups are replaced by symmetric groups. The foundations for the theory of symmetric homology of algebras are developed in the context of crossed simplicial groups using…

Algebraic Topology · Mathematics 2008-07-29 Shaun Ault

For a manifold M we define a structure on the group action of Diff(M) on the smooth functions on M which reduces to the usual differential geometry upon differentiation at zero along the one-parameter groups of Diff(M). This ``integrated…

High Energy Physics - Theory · Physics 2007-05-23 Hendrik Grundling

Power operations in the homology of infinite loop spaces, and $H_\infty$ or $E_\infty$ ring spectra have a long history in Algebraic Topology. In the case of ordinary mod p homology for a prime p, the power operations of Kudo, Araki, Dyer…

Algebraic Topology · Mathematics 2014-12-19 Andrew Baker

We classify Hopf actions of Taft algebras T(n) on path algebras of quivers, in the setting where the quiver is loopless, finite, and Schurian. As a corollary, we see that every quiver admitting a faithful Z_n-action (by directed graph…

Quantum Algebra · Mathematics 2016-02-24 Ryan Kinser , Chelsea Walton

Among the ergodic actions of a compact quantum group $\mathbb{G}$ on possibly non-commutative spaces, those that are {\it embeddable} are the natural analogues of actions of a compact group on its homogeneous spaces. These can be realized…

Quantum Algebra · Mathematics 2017-08-23 Alexandru Chirvasitu , Souleiman Omar Hoche

For each of the groups $G = O(2), SU(2), U(2)$, we compute the integral and $\mathbb{F}_2$-cohomology rings of $B_\text{com} G$ (the classifying space for commutativity of $G$), the action of the Steenrod algebra on the mod 2 cohomology,…

Algebraic Topology · Mathematics 2019-07-17 Omar Antolín-Camarena , Simon Gritschacher , Bernardo Villarreal

In the article, two implementations of the representation of the complex Lie algebra $\mathfrak{sl}_2$ on the algebra of symmetric polynomials $\Lambda_n$ by differential operators are proposed. The realizations of irreducible…

Combinatorics · Mathematics 2024-08-16 Leonid Bedratyuk

We show that the simply-connected four-manifolds which admit locally linear, homologically trivial actions by rank two finite abelian groups are homeomorphic to connected sums of CP^2, -CP^2, and S^2 x S^2 (with one exception: pseudofree…

Geometric Topology · Mathematics 2007-07-26 Michael P. McCooey

Building up on work of Epstein, May and Drury, we define and investigate the mod $p$ Steenrod operations on the de Rham cohomology of smooth algebraic stacks over a field of characteristic $p>0$. We then compute the action of the operations…

Algebraic Geometry · Mathematics 2021-07-01 Federico Scavia

We study finite abelian group actions on weakly Lefschetz cohomologically symplectic (WLS) manifolds, a collection of manifolds that includes all compact connected Kaehler manifolds. We prove that for any WLS manifold $X$ there exists a…

Algebraic Topology · Mathematics 2025-09-10 Ignasi Mundet i Riera