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We study Legendrian singularities arising in complex contact geometry. We define a one-parameter family of bases in the ring of Legendrian characteristic classes such that any Legendrian Thom polynomial has nonnegative coefficients when…

Algebraic Geometry · Mathematics 2011-12-08 Malgorzata Mikosz , Piotr Pragacz , Andrzej Weber

We show that, in the framework of covariant Hamiltonian field theory, a degenerate almost regular quadratic Lagrangian $L$ admits a complete set of non-degenerate Hamiltonian forms such that solutions of the corresponding Hamilton…

High Energy Physics - Theory · Physics 2009-10-31 L. Mangiarotti , G. Sardanashvily

Fock and Goncharov conjectured that the indecomposable universally positive (i.e., atomic) elements of a cluster algebra should form a basis for the algebra. This was shown to be false by Lee-Li-Zelevinsky. However, we find that the theta…

Quantum Algebra · Mathematics 2019-02-20 Travis Mandel

We study the topological index of some irregular surfaces that we call generalized Lagrangian. We show that under certain hypotheses on the base locus of the Lagrangian system the topological index is non-negative. For the minimal surfaces…

Algebraic Geometry · Mathematics 2007-05-23 M. A. Barja , J. C. Naranjo , G. P. Pirola

In this paper we explore the combinatorics of the non-negative part (G/P)+ of a cominuscule Grassmannian. For each such Grassmannian we define Le-diagrams -- certain fillings of generalized Young diagrams which are in bijection with the…

Combinatorics · Mathematics 2007-10-17 Thomas Lam , Lauren Williams

We describe an iterative construction of Lagrangian tori in the complex Grassmannian $\operatorname{Gr}(k,n)$, based on the cluster algebra structure of the coordinate ring of a mirror Landau-Ginzburg model proposed by Marsh-Rietsch. Each…

Symplectic Geometry · Mathematics 2023-08-08 Marco Castronovo

Tropical algebraic geometry is the geometry of the tropical semiring (R, min, +). The theory of total positivity is a natural generalization of the study of matrices with all minors positive. In this paper we introduce the totally positive…

Combinatorics · Mathematics 2007-05-23 David Speyer , Lauren K. Williams

Geodesics in the space of positive Lagrangian submanifolds are solutions of a fully non-linear degenerate elliptic PDE. We show that a geodesic segment in the space of positive Lagrangians corresponds to a one parameter family of special…

Symplectic Geometry · Mathematics 2026-03-27 Jake P. Solomon , Amitai M. Yuval

We show that the tropical projective Grassmannian of planes is homeomorphic to a closed subset of the analytic Grassmannian in Berkovich's sense by constructing a continuous section to the tropicalization map. Our main tool is an explicit…

Algebraic Geometry · Mathematics 2014-03-12 Maria Angelica Cueto , Mathias Haebich , Annette Werner

In this paper we discuss a couple of observations related to polynomial convexity. More precisely, (i) We observe that the union of finitely many disjoint closed balls with centres in $\cup_{\theta\in[0,\pi/2]}e^{i\theta}V$ is polynomially…

Complex Variables · Mathematics 2019-09-11 Sushil Gorai

In this paper we study the Grassmannian of submodules of a given dimension inside a finitely generated projective module $P$ for a finite dimensional algebra $\Lambda$ over an algebraically closed field. The orbit of such a submodule $C$…

Representation Theory · Mathematics 2017-08-10 Frauke M. Bleher , Ted Chinburg , Birge Huisgen-Zimmermann

We provide a criterion for a coherent sheaf to be an Ulrich sheaf in terms of a certain bilinear form on its global sections. When working over the real numbers we call it a positive Ulrich sheaf if this bilinear form is symmetric or…

Algebraic Geometry · Mathematics 2023-07-18 Christoph Hanselka , Mario Kummer

It has been shown that spaces of geodesic triangulations of surfaces with negative curvature are contractible. Here we propose an approach aiming to prove that the spaces of geodesic triangulations of a surface with negative curvature are…

Geometric Topology · Mathematics 2024-08-27 Yanwen Luo , Tianqi Wu , Xiaoping Zhu

In this note we show that the nonnegative part of a proper complex toric variety has the homeomorphism type of a sphere, and consequently that the nonnegative part has a natural structure of a cell complex. This extends previous results of…

Algebraic Geometry · Mathematics 2025-04-21 Mike Roth

In this thesis we study asymptotic behavior of projective embeddings of abelian varieties and their amoebas. The projective embeddings are given by theta functions. It is known that a Lagrangian fibration of the abelian variety determines a…

Differential Geometry · Mathematics 2007-05-23 Yuichi Nohara

We derive the gravitational Lagrangian to all orders of curvature when the canonical constraint algebra is deformed by a phase space function as predicted by some studies into loop quantum cosmology. The deformation function seems to be…

General Relativity and Quantum Cosmology · Physics 2020-11-25 Rhiannon Cuttell , Mairi Sakellariadou

In this article we consider theta-expanded noncommutative gauge field theory, constructed at the first order in noncommutative parameter theta, as an effective, anomaly free theory, with one-loop renormalizable gauge sector. Related…

High Energy Physics - Phenomenology · Physics 2008-11-26 Josip Trampetic

In this short note, we construct a family of non-regular, and therefore non-decomposable, Lagrangian concordances between Lagrangian fillable Legendrian knots in the standard contact 3-dimensional sphere. More precisely, for every…

Symplectic Geometry · Mathematics 2025-09-18 Georgios Dimitroglou Rizell , Roman Golovko

We present a method to study the time variation of the orbital parameters of a Post-Keplerian binary system undergoing a generic external perturbation. The method is the relativistic extension of the planetary Lagrangian equations. The…

General Relativity and Quantum Cosmology · Physics 2009-10-30 Mirco Calura , Pierluigi Fortini , Enrico Montanari

We construct monotone Lagrangian tori in the standard symplectic vector space, in the complex projective space and in products of spheres. We explain how to classify these Lagrangian tori up to symplectomorphism and Hamiltonian isotopy, and…

Symplectic Geometry · Mathematics 2010-04-01 Yuri Chekanov , Felix Schlenk