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Related papers: Picard-Lefschetz theory and dilating C^*-actions

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Let $X\to C$ be an elliptic surface with integral fibers and a section. The Hilbert scheme $X^{[n]}$ fibers over $C^{[n]}$. We construct a commutative group scheme over the entire base $C^{[n]}$ that embeds as an open subscheme of the…

Algebraic Geometry · Mathematics 2025-10-01 David Zhiyuan Bai

We prove the index theorem for elliptic operators acting on sections of bundles where fiber is equal to a projective module over a C*-algebra, in the situation of action of a compact Lie group on this algebra as well as on the total space…

Operator Algebras · Mathematics 2007-05-23 Evgenij V. Troitsky

In a compact, symplectic real manifold, i.e supporting an antisymplectic involution, we use Donaldson's construction to build a codimension 2 symplectic submanifold invariant under the action of the involution. If the real part of the…

Symplectic Geometry · Mathematics 2007-12-06 Damien Gayet

We use Lefschetz pencil methods to derive structural results about Fukaya categories of Calabi-Yau hypersurfaces; in particular, concerning their dependence on the Novikov parameter. Warning to the reader: the arguments in this paper cite…

Symplectic Geometry · Mathematics 2021-06-03 Paul Seidel

In this paper we classify symplectic Lefschetz fibrations (with empty base locus) on a four-manifold which is the product of a three-manifold with a circle. This result provides further evidence in support of the following conjecture…

Differential Geometry · Mathematics 2014-11-11 Weimin Chen , Rostislav Matveyev

The Lefschetz algebra $L^*(X)$ of a smooth complex projective variety $X$ is the subalgebra of the cohomology algebra of $X$ generated by divisor classes. We construct smooth complex projective varieties whose Lefschetz algebras do not…

Algebraic Geometry · Mathematics 2016-09-29 June Huh , Botong Wang

In part I, using the theory of $\infty$-categories, we constructed a natural ``continuous action'' of $\operatorname {Ham} (M, \omega) $ on the Fukaya category of a closed monotone symplectic manifold. Here we show that this action is…

Symplectic Geometry · Mathematics 2023-02-06 Yasha Savelyev

We develop techniques to construct explicit symplectic Lefschetz fibrations over the 2-sphere with any prescribed signature and any spin type when the signature is divisible by 16. This solves a long-standing conjecture on the existence of…

Geometric Topology · Mathematics 2020-10-23 R. Inanc Baykur , Noriyuki Hamada

Let $G$ be a semi-simple real Lie group of real rank one and $\Gamma$ be a discrete subgroup in $G$ such that $\Gamma \backslash G$ has finite volume. We introduce a new group $C^*$-algebra $C^*_r(G, \Gamma)$, which provides a natural…

K-Theory and Homology · Mathematics 2025-07-30 Yanli Song

Given a symplectic manifold $M$, we may define an operad structure on the the spaces $\op^k$ of the Lagrangian submanifolds of $(\bar{M})^k\times M$ via symplectic reduction. If $M$ is also a symplectic groupoid, then its multiplication…

Symplectic Geometry · Mathematics 2020-05-29 Alberto S. Cattaneo , Benoit Dherin , Giovanni Felder

We construct symplectic submanifolds of symplectic manifolds with contact border. The boundary of such submanifolds is shown to be a contact submanifold of the contact border. We also give a topological characterization of the constructed…

Symplectic Geometry · Mathematics 2007-05-23 Francisco Presas

As a generalization of the Exel-Pardo's notion of self-similar graph, we introduce self-similar group actions on ultragraphs and their $C^*$-algebras. We then approach to the $C^*$-algebras by inverse semigroup and tight groupoid models.

Operator Algebras · Mathematics 2025-05-20 Hossein Larki , Najmeh Rajabzadeh-Hasiri

We show how to construct broken, achiral Lefschetz fibrations on arbitrary smooth, closed, oriented 4-manifolds. These are generalizations of Lefschetz fibrations over the 2-sphere, where we allow Lefschetz singularities with the…

Geometric Topology · Mathematics 2014-11-11 David T. Gay , Robion Kirby

Partial actions of groups on C*-algebras and the closely related actions and coactions of Hopf algebras received much attention over the last decades. They arise naturally as restrictions of their global counterparts to non-invariant…

Operator Algebras · Mathematics 2018-11-14 Franziska Kraken , Paula Quast , Thomas Timmermann

We consider product 4--manifolds S^1 X M, where M is a closed, connected and oriented 3-manifold. We prove that if S^1 X M admits a complex structure or a Lefschetz or Seifert fibration, then the following statement is true: S^1 X M admits…

Symplectic Geometry · Mathematics 2007-05-23 Tolga Etgu

In this paper we construct, in all odd complex dimensions, pairs of Liouville domains W_0 and W_1 which are diffeomorphic to the cotangent bundle of the sphere with one extra subcritical handle, but are not symplectomorphic. While W_0 is…

Symplectic Geometry · Mathematics 2012-11-01 Maksim Maydanskiy

We introduce filtered cohomologies of differential forms on symplectic manifolds. They generalize and include the cohomologies discussed in Paper I and II as a subset. The filtered cohomologies are finite-dimensional and can be associated…

Symplectic Geometry · Mathematics 2014-05-06 Chung-Jun Tsai , Li-Sheng Tseng , Shing-Tung Yau

We develop a set of tools for doing computations in and of (partially) wrapped Fukaya categories. In particular, we prove (1) a descent (cosheaf) property for the wrapped Fukaya category with respect to so-called Weinstein sectorial…

Symplectic Geometry · Mathematics 2023-08-29 Sheel Ganatra , John Pardon , Vivek Shende

We define proper, free and commuting partial actions on upper semicontinuous bundles of $C^*-$algebras. With such, we construct the $C^*-$algebra induced by a partial action and a partial actions on that algebra. Using those action we give…

Operator Algebras · Mathematics 2012-09-20 Damián Ferraro

We present an approach to constructing broken Lefschetz fibrations (BLFs) $f:X\rightarrow S^2$ from a handle decomposition of a 4-manifold $X$. Given a handle decomposition as input these techniques yield explicit descriptions of the BLFs,…

Geometric Topology · Mathematics 2015-12-01 Mark C. Hughes