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We study hamiltonian actions of compact groups in the presence of compatible involutions. We show that the lagrangian fixed point set on the symplectically reduced space is isomorphic to the disjoint union of the involutively reduced spaces…

Symplectic Geometry · Mathematics 2007-05-23 Philip Foth

In a previous paper the authors developed an operator-algebraic approach to Lewis Bowen's sofic measure entropy that yields invariants for actions of countable sofic groups by homeomorphisms on a compact metrizable space and by…

Dynamical Systems · Mathematics 2013-07-22 David Kerr , Hanfeng Li

In this paper, we consider minimal equicontinuous actions of discrete countably generated groups on Cantor sets, obtained from the arboreal representations of absolute Galois groups of fields. In particular, we study the asymptotic…

Dynamical Systems · Mathematics 2018-11-07 Olga Lukina

We define a certain class of simple varieties over a field $k$ by a constructive recipe and show how to control their (equivariant) truncating invariants. Consequently, we prove that on simple varieties: (i) if $k=\overline{k}$ and…

Algebraic Geometry · Mathematics 2026-04-20 Jakub Löwit

We construct the odd symplectic structure and the equivariant even (pre)symplectic one from it on the space of differential forms on the Riemann manifold. The Poincare -- Cartan like invariants of the second structure define the equivariant…

High Energy Physics - Theory · Physics 2008-02-03 A. Nersessian

We restate the notion of orthogonal calculus in terms of model categories. This provides a cleaner set of results and makes the role of O(n)-equivariance clearer. Thus we develop model structures for the category of n-polynomial and…

Algebraic Topology · Mathematics 2015-03-17 David Barnes , Peter Oman

In this paper, we introduce the notion of relation type of analytic and formal algebras and prove that it is well-defined and invariant by describing this notion in terms of the Andr\'e-Quillen homology and using the Jacobi-Zariski long…

Algebraic Geometry · Mathematics 2022-08-04 Maryam Akhavin , Abbas Nasrollah Nejad

We consider topological groupoids in finite and also in a compact settings. In the initial sections, we introduce definitions of typical observables and we studied them in the context of statistical mechanics and quantum mechanics. We…

Mathematical Physics · Physics 2023-03-22 Artur O. Lopes , Marcos Sebastian , Victor Vargas

We observe that most known results of the form "v is not a finite-type invariant" follow from two basic theorems. Among those invariants which are not of finite type, we discuss examples which are "ft-independent" and examples which are…

Geometric Topology · Mathematics 2007-05-23 Theodore Stanford , Rolland Trapp

Every $(\infty, n)$-category can be approximated by its tower of homotopy $(m, n)$-categories. In this paper, we prove that the successive stages of this tower are classified by k-invariants, analogously to the classical Postnikov tower for…

Algebraic Topology · Mathematics 2025-05-21 Yonatan Harpaz , Joost Nuiten , Matan Prasma

We suggest a homotopical description of the Poisson bracket invariants for tuples of closed sets in symplectic manifolds. It implies that these invariants depend only on the union of the sets along with topological data.

Symplectic Geometry · Mathematics 2018-06-19 Yaniv Ganor

The adjoint method introduced in [Eva] and [Tra] is used, to construct analogs to the Aubry-Mather measures for non convex Hamiltonians. More precisely, a general construction of probability measures, that in the convex setting agree with…

Analysis of PDEs · Mathematics 2012-01-04 Filippo Cagnetti , Diogo Gomes , Hung Tran

In the first part of this series, we defined an equivariant index without assuming the group acting or the orbit space of the action to be compact. This allowed us to generalise an index of deformed Dirac operators, defined for compact…

K-Theory and Homology · Mathematics 2016-02-10 Peter Hochs , Yanli Song

We describe a homotopical version of the relational and gluing models of type theory, and generalize it to inverse diagrams and oplax limits. Our method uses the Reedy homotopy theory on inverse diagrams, and relies on the fact that Reedy…

Category Theory · Mathematics 2019-02-20 Michael Shulman

We assign some kind of invariant manifolds to a given integrable PDE (its discrete or semi-discrete variant). First, we linearize the equation around its arbitrary solution $u$. Then we construct a differential (respectively, difference)…

Exactly Solvable and Integrable Systems · Physics 2018-04-25 Ismagil Habibullin , Aigul Khakimova

We consider iterated function systems (finite or countable), together with linear and continuous operators on Hilbert spaces, which enable us to construct Markov-type operators. Under suitable conditions, these Markov-type operators have…

Classical Analysis and ODEs · Mathematics 2017-01-30 Ion Chiţescu , Loredana Ioana , Radu Miculescu , Lucian Niţă

These lectures centered around the Kempf-Ness theorem, which describes the equivalence between notions of quotient in symplectic and algebraic geometry. The text also describes connections to invariant theory, such existence of invariants…

Symplectic Geometry · Mathematics 2011-06-30 Christopher T. Woodward

We generalize the classical semiregularity theorem of Buchweitz and Flenner to the setting of noncommutative algebraic geometry, with group actions. This applies in particular to twisted derived categories, in which case it answers a…

Algebraic Geometry · Mathematics 2026-04-02 Alexander Perry

This paper is the second in a series investigating cartesian closed varieties. In first of these, we showed that every non-degenerate finitary cartesian variety is a variety of sets equipped with an action by a Boolean algebra B and a…

Operator Algebras · Mathematics 2024-08-06 Richard Garner

We define and study bivariant equivariant periodic cyclic homology for actions of ample groupoids. In analogy to the group case, we show that the theory satisfies homotopy invariance, stability, and excision in both variables. We also prove…

K-Theory and Homology · Mathematics 2026-02-20 Francesco Pagliuca , Christian Voigt