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A locally-built, LLM-digested index of recent arXiv papers in quant finance, geometry/topology, and statistical ML — keyword search served straight from SQLite on this machine.

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48 results for equivariant bijection

The elaboration of new quantization methods has recently developed the interest in the study of subalgebras of the Lie algebra of polynomial vector fields over a Euclidean space. In this framework, these subalgebras define maximal equivariance conditions that one can impose on a linear bijection between observables tha…

2000-09-28abs ↗pdf ↗

We introduce linear Dirac and generalized complex structures on Cartan geometries and give criteria for Dirac subalgebras of $\frkg\ltimes\frkg^*$ representing Dirac structures on a Cartan geometry. We prove that there is a bijection between the linear generalized structures on a torsion free Cartan geometry and the eq…

2012-04-26abs ↗pdf ↗

The spaces of linear differential operators on Rn{\mathbb{R}}^n acting on tensor densities of degree λλ and the space of functions on TRnT^*{\mathbb{R}}^n which are polynomial on the fibers are not isomorphic as modules over the Lie algebra $\Vect({\mathbb{R}}^n)$ of vector fields on Rn{\mathbb{R}}^n. However, these mo…

1998-09-11abs ↗pdf ↗

Study of symplectomorphisms on ruled surfaces under circle actions.

problem Homotopy type of equivariant symplectomorphisms on rational ruled surfaces.
method Analysis of action on compatible and invariant almost complex structures, use of Delzant's and Karshon's classifications.
result Equivariant symplectomorphisms are homotopy equivalent to tori or their pushout.

In the present paper we find a bijection between the set of small covers over an nn-cube and the set of acyclic digraphs with nn labeled nodes. Using this, we give a formula of the number of small covers over an nn-cube (generally, a product of simplices) up to Davis-Januszkiewicz equivalence classes and $\mathbf{Z}…

2008-02-14abs ↗pdf ↗

We study natural bases for two constructions of the irreducible representation of the symmetric group corresponding to [n,n,n][n,n,n]: the {\em reduced web} basis associated to Kuperberg's combinatorial description of the spider category; and the {\em left cell basis} for the left cell construction of Kazhdan and Lusztig. I…

2013-07-24abs ↗pdf ↗

Geometric correspondence between spinors and horospheres in hyperbolic space.

problem Understanding the relationship between spinors and horospheres in hyperbolic geometry.
method Detailed exposition and step-by-step construction of the spinor--horosphere correspondence.
result Spinor--horosphere correspondence is a smooth, SL(2,C)SL(2,\mathbb{C})-equivariant bijection.

We prove a theorem on equivariant maps implying the following two corollaries: (1) Let N and M be compact orientable n-manifolds with boundaries such that M\subset N, the inclusion M\to N induces an isomorphism in integral cohomology, both M and N have (n-d-1)-dimensional spines and m > max {n+2, (3n+1-d)/2} . Then the…

2012-07-05abs ↗pdf ↗

A bijection proves a polynomial volume for genus-0 hyperbolic surfaces with boundaries.

problem Proving the Weil-Petersson volume polynomial in boundary lengths for genus-0 surfaces.
method Generalizing a tree bijection to handle geodesic boundaries, extending spine construction.
result Explicit formula for three-point function in Weil-Petersson random surfaces.

We identify causal models with unobserved confounding using bijective generation mechanisms.

problem Identifying causal relationships with unobserved confounders.
method Establish counterfactual identifiability for BGMs and propose a learning method.
result Learned BGMs enable efficient counterfactual estimation.

Improved ANN-based Monte Carlo simulation for Higgs decay events.

problem Accurate simulation of Higgs boson decay events.
method Monte Carlo simulation using an Artificial Neural Network (ANN) with improved training algorithm.
result The ANN simulation of Higgs decay is within 0.7% of the true value and achieves 26% unweighting efficiency.

Given a pair of number fields with isomorphic rings of adeles, we construct bijections between objects associated to the pair. For instance we construct an isomorphism of Brauer groups that commutes with restriction. We additionally construct bijections between central simple algebras, maximal orders, various Galois co…

2015-05-18abs ↗pdf ↗

The classical Fundamental Theorem of Affine Geometry states that for n2n\geq 2, any bijection of nn-dimensional Euclidean space that maps lines to lines (as sets) is given by an affine map. We consider an analogous characterization of affine automorphisms for compact quotients, and establish it for tori: A bijection o…

2016-12-17abs ↗pdf ↗

Let XX be a topological space and f:XXf:X\to X a bijection. Let C(X,f){\mathcal C}(X,f) be a set of integers such that an integer nn is an element of C(X,f){\mathcal C}(X,f) if and only if the bijection fn:XXf^n:X\to X is continuous. A subset SS of the set of integers Z{\mathbb Z} is said to be realizable if there is a topologi…

2013-10-07abs ↗pdf ↗

We introduce an equivalence relation, called stable equivalence, on knot diagrams and closed curves on surfaces. We give bijections between the set of abstract knots, the set of virtual knots, and the set of the stable equivalence classes of knot diagrams on surfaces. Using these bijections, we define concordance and l…

2000-08-16abs ↗pdf ↗

Normalising flows (NFS) map two density functions via a differentiable bijection whose Jacobian determinant can be computed efficiently. Recently, as an alternative to hand-crafted bijections, Huang et al. (2018) proposed neural autoregressive flow (NAF) which is a universal approximator for density functions. Their fl…

2019-04-09abs ↗pdf ↗

We classify the torsion pairs in a tube category and show that they are in bijection with maximal rigid objects in the extension of the tube category containing the Pruefer and adic modules. We show that the annulus geometric model for the tube category can be extended to the larger category and interpret torsion pairs…

2011-12-28abs ↗pdf ↗

Method flattens complex surfaces with consistent density and shape.

problem Shape deformations and local geometric distortions in density-equalizing maps for multiply-connected surfaces.
method Formulates density diffusion as a quasiconformal flow, solving an energy minimization problem involving the Beltrami coefficient to ensure bijectivity and control distortion.
result Achieves optimal parameterization of multiply-connected surfaces with bijective and controlled geometric distortions.

We prove a Lipschitz-Volume rigidity theorem in Alexandrov geometry, that is, if a 1-Lipschitz map f ⁣:X=⨿XYf\colon X=\amalg X_\ell\to Y between Alexandrov spaces preserves volume, then it is a path isometry and an isometry when restricted to the interior of XX. We furthermore characterize the metric structure on YY with re…

2011-10-25abs ↗pdf ↗

Virtual braids are a combinatorial generalization of braids. We present abstract braids as equivalence classes of braid diagrams on a surface, joining two distinguished boundary components. They are identified up to isotopy, compatibility, stability and Reidemeister moves. We show that virtual braids are in a bijective…

2014-02-03abs ↗pdf ↗

A bijection preserving horocycles/hypercycles is an isometry in hyperbolic plane.

problem Understanding transformations of constant curvature curves in hyperbolic geometry.
method Analyzing bijections that map horocycles to horocycles and hypercycles to hypercycles.
result Every abstract automorphism of geodesic/horocycles/hypercycles graphs is induced by an earthquake map/isometry.

Study on K3 surfaces' collapsing and special Kähler structures.

problem Understanding the structure of K3 surfaces' collapsing metrics.
method Analyzing M2\mathfrak{M}_2 and establishing connections to SKSs and Jacobian elliptic K3 surfaces.
result Established a bijection between integral singular SKSs on P1\mathbb{P}^1 and Jacobian elliptic K3 surfaces.

Characterizes smiles in delta satisfying specific conditions.

problem Characterizing no butterfly arbitrage smiles in delta.
method Using parametrization of the smile in delta, we characterize the set of smiles.
result Obtained a parametrization of the set via one real number and three positive functions.

For a Lie-Rinehart algebra (A,L), generators for the Gerstenhaber algebra Λ_A L correspond bijectively to right (A,L)-connections on A in such a way that B-V structures correspond to right (A,L)-module structures on A. When L is projective as an A-module, given an exact generator \partial, the homology of the B-V algeb…

1997-04-09abs ↗pdf ↗

Study of invariants on manifolds with boundary involving equivariant spectral flow and η-invariants.

problem Equivariant invariants on manifolds with boundary.
method Analysis of Dirac operators, winding numbers, spectral flow, Maslov indices, and η-invariants.
result Established relation between equivariant η-invariants and Maslov triple indices.