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We give a simple proof that the straightforward generalisation of clique-width to arbitrary structures can be unbounded on structures of bounded tree-width. This can be corrected by allowing fusion of elements.

Logic in Computer Science · Computer Science 2008-06-03 Hans Adler , Isolde Adler

In this document we present a twistor correspondence for half-flat almost-Grassmannian structures on real and complex manifolds. We provide foundational results regarding local theory in the complex setting and a global correspondence when…

Differential Geometry · Mathematics 2023-04-18 Matthew Lam

The goal of this paper, using lifting theory it is to produce almost paracomplex struc- tures on the tangent bundle of almost Lorentzian r-paracontact manifold endowed with almost Lorentzian r-paracontact structure. Finally, we discuss the…

Differential Geometry · Mathematics 2009-03-03 Mehmet Tekkoyun

We first make a little survey of the twistor theory for hypercomplex, generalized hypercomplex, quaternionic or generalized quaternionic manifolds. This last theory was iniated by Pantilie, who shows that any generalized almost quaternionic…

Differential Geometry · Mathematics 2016-01-18 Guillaume Deschamps

We give a complete proof of the fact that a contact structure that is sufficiently close to a Reebless foliation is universally tight.

Geometric Topology · Mathematics 2013-12-12 Jonathan Bowden

We extend a result of M. Katz on conformal systoles to all four-manifolds with b^+=1 which have odd intersection form. The same result holds for all four-manifolds with b^+=1 with even intersection form and which are symplectic or satisfy…

Differential Geometry · Mathematics 2009-07-16 M. J. D. Hamilton

We consider certain fiber bundles over a paraquaternionic contact manifolds, called twistor and reflector spaces, and show that these carry an intrinsic geometric structure that is always integrable.

Differential Geometry · Mathematics 2024-09-04 Stefan Ivanov , Ivan Minchev , Marina Tchomakova

This article describes the following results which relate to each other; i) convergence of high dimensional contact structure to codimension one foliation with Reeb component, ii) relation between Nil-type and Sol-type contact submanifolds…

Geometric Topology · Mathematics 2015-05-28 Atsuhide Mori

We introduce generalized almost contact structures which admit the $B$-field transformations on odd dimensional manifolds. We provide definition of generalized Sasakain structures from the view point of the generalized almost contact…

Differential Geometry · Mathematics 2012-12-27 Ken'ichi Sekiya

We study orbifolds of two-dimensional topological field theories using defects. If the TFT arises as the twist of a superconformal field theory, we recover results on the Neveu-Schwarz and Ramond sectors of the orbifold theory as well as…

High Energy Physics - Theory · Physics 2014-09-16 Ilka Brunner , Nils Carqueville , Daniel Plencner

We give an algorithm which produces infinitely many pairwise exotic Stein fillings of the same contact 3-manifolds, applying positive allowable Lefschetz fibrations over the disk. As a corollary, for a large class of Stein fillings, we…

Geometric Topology · Mathematics 2014-07-02 Kouichi Yasui

In this paper we propose a theory of contact invariants and open string invariants, which are generalizations of the relative invariants. We introduce two moduli spaces $\bar{\mathcal{M}}_{A}(M^{+},C,g,m+\nu,{\bf y},{\bf…

Symplectic Geometry · Mathematics 2015-01-27 An-Min Li , Li Sheng

We present a new, completely three-dimensional proof of the fact, due to Gabai-Eliashberg-Thurston, that every closed, oriented, irreducible 3-manifold with nonzero second homology carries a universally tight contact structure.

Geometric Topology · Mathematics 2007-05-23 Ko Honda , William H. Kazez , Gordana Matic

Let M be a closed (n-1)-connected 2n-dimensional smooth manifold with n > 2. In terms of the system of invariants for such manifolds introduced by Wall, we obtain necessary and sufficient conditions for M to admit an almost complex…

Algebraic Topology · Mathematics 2011-10-11 Huijun Yang

We construct infinitely many families of Lorenz knots that are satellites but not cables, giving counterexamples to a conjecture attributed to Morton. We amend the conjecture to state that Lorenz knots that are satellite have companion a…

Geometric Topology · Mathematics 2022-11-14 Thiago de Paiva , Jessica S. Purcell

In this note we explore the variation of Hodge structures associated to the orbifold Landau-Ginzburg B-model whose superpotential has two variables. We extend the Getzler-Gauss-Manin connection to Hochschild chains twisted by group action.…

Mathematical Physics · Physics 2019-04-23 Weiqiang He , Si Li , Yifan Li

We prove that an infinite family of virtually overtwisted tight contact structures discovered by Honda on certain circle bundles over surfaces admit no symplectic semi-fillings. The argument uses results of Mrowka, Ozsvath and Yu on the…

Symplectic Geometry · Mathematics 2014-11-11 Paolo Lisca , Andras I Stipsicz

We reformulate the monodromy relations of open-string scattering amplitudes as boundary terms of twisted homologies on the configuration spaces of Riemann surfaces of arbitrary genus. This allows us to write explicit linear relations…

High Energy Physics - Theory · Physics 2020-01-29 Eduardo Casali , Sebastian Mizera , Piotr Tourkine

We prove, for a class of contact manifolds, that the universal cover of the group of contact diffeomorphisms carries a natural partial order. It leads to a new viewpoint on geometry and dynamics of contactomorphisms. It gives rise to…

Symplectic Geometry · Mathematics 2007-05-23 Yakov Eliashberg , Leonid Polterovich

We prove that any quasitoric manifold $M^{2n}$ admits a $T^n$-invariant almost complex structure if and only if $M$ admits a positive omniorientation. In particular, we show that all obstructions to existence of $T^n$-invariant almost…

Algebraic Topology · Mathematics 2009-04-28 Andrei Kustarev