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arXiv research

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.

168,742 papers · 148 categories

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204408611815 · Jun 202019922001200920172026
48 results for purely unrectifiable sets

We establish Marstrand-type projection theorems for orthogonal projections along geodesics onto m-dimensional subspaces of hyperbolic nn-space by a geometric argument. Moreover, we obtain a Besicovitch-Federer type characterization of purely unrectifiable sets in terms of these hyperbolic orthogonal projections.

2018-07-30abs ↗pdf ↗

We construct new examples of normal (metric) currents using inverse systems of cube complexes. For any N2N\ge 2 we provide examples of NN-dimensional normal currents whose associated vector fields are simple, and whose supports are purely 22-unrectifiable and have Nagata dimension NN. We show that in ll^\infty norm…

2015-08-04abs ↗pdf ↗

We find necessary and sufficient conditions for a Lipschitz map f:REXf:\mathbb{R}E\to X, into a metric space to have the image with the kk-dimensional Hausdorff measure equal zero, Hk(f(E))=0H^k(f(E))=0. An interesting feature of our approach is that despite the fact that we are dealing with arbitrary metric spaces, we employ a …

2014-03-06abs ↗pdf ↗

Study contact 3-manifolds using sub-Riemannian geometry, proving new properties of their Lipschitz homotopy groups.

problem Characterize the Lipschitz homotopy groups of contact 3-manifolds.
method Sub-Riemannian geometry, geometric measure theory, biLipschitz equivalence, purely unrectifiable sets.
result Contact 3-manifolds are K(π,1)K(\pi,1) spaces with uncountably generated first homotopy groups.

We give an alternative proof for the fact that in nn-dimensional Alexandrov spaces with curvature bounded below there exists a unique optimal transport plan from any purely (n1)(n-1)-unrectifiable starting measure, and that this plan is induced by an optimal map.

2018-03-27abs ↗pdf ↗

New insights into integrability and rectifiability in sub-Riemannian geometry.

problem Understanding rectifiability in sub-Riemannian spaces.
method Refined Frobenius Theorem for non-involutive distributions, new metric space class.
result Carnot-Carathéodory spaces are extremal in rectifiability.

This paper is related to the problem of finding a good notion of rectifiability in sub-Riemannian geometry. In particular, we study which kind of results can be expected for smooth hypersurfaces in Carnot groups. Our main contribution will be a consequence of the following result: there exists a CC^{\infty} hypersurfa…

2019-10-28abs ↗pdf ↗

Two virtual link diagrams are homotopic if one may be transformed into the other by a sequence of virtual Reidemeister moves, classical Reidemeister moves, and self crossing changes. We recall the pure virtual braid group. We then describe the set of pure virtual braids that are homotopic to the identity braid.

2007-04-23abs ↗pdf ↗

This article is dedicate to cabling on virtual braids. This construction gives a new generating set for the virtual pure braid group VPnVP_n. Consequently we describe VP4VP_4 as HNN-extension. As an application to classical braids, we find a new presentation of the Artin pure braid group P4P_4 in terms of the cabled gene…

2019-05-18abs ↗pdf ↗

The paper tackles pure exploration in multi-armed bandits with low rank structure using oblivious sampling.

problem Pure exploration in multi-armed bandits with low rank reward sequences.
method The approach involves separating the exploration strategy from feedback, using oblivious sampling, and incorporating kernel information of reward vectors.
result Efficient algorithms with regret bound O(d(lnN)/n)O(d\sqrt{(\ln N)/n}) for both time-varying and fixed cases, with a lower bound gap of O(lnN)O(\sqrt{\ln N}).

New random forest method provides optimal rates and confidence bands.

problem Improving random forest regression rates and constructing confidence bands.
method Proposed Ehrenfest centered purely random forests achieve optimal rates; used Gaussian approximation for supremum of empirical processes.
result Explicit asymptotic uniform confidence bands constructed for both random forest types.

This paper tackles combinatorial pure exploration for dueling bandits, aiming to find the best candidate-position match.

problem Finding the best candidate-position match in a dueling bandit setting.
method The paper adapts combinatorial pure exploration for multi-armed bandits to dueling bandits, considering both Borda winner and Condorcet winner cases. It designs PAC and exact algorithms for Borda winner and a fully polynomial time approximation scheme (FPTAS) for Condorcet winner.
result The paper introduces the first algorithm with polynomial running time per round for identifying the Condorcet winner in CPE-DB.

We use a variation on the commutator collection process to characterize those pure braids which become trivial when any one strand is deleted, or, more generally, those pure braids which become trivial when all the strands in any one of a list of sets of strands is deleted.

1999-07-12abs ↗pdf ↗

Framework purifies approximate differential privacy to pure differential privacy.

problem Achieving pure differential privacy from approximate differential privacy.
method Randomized post-processing with calibrated noise to eliminate δ parameter.
result First statistically and computationally efficient reduction from approximate DP to pure DP.

This work introduces CAET, an algorithm for cost-aware pairwise pure exploration.

problem Identifying optimal arm pairs with varying costs in multi-armed bandits.
method Introduces a framework for pairwise pure exploration with arm-specific costs, derives a lower bound, and proposes CAET algorithm.
result CAET optimizes cumulative cost and approaches the lower bound asymptotically.

In this article, we investigate various properties of the pure virtual braid group PV_3. From its canonical presentation, we obtain a free product decomposition of PV_3. As a consequence, we show that PV_3 is residually torsion free nilpotent, which implies that the set of finite type invariants in the sense of Goussar…

2009-06-09abs ↗pdf ↗

Unified algorithm for efficient pure exploration using dual variables.

problem Efficiently achieving a specific goal through adaptive experimentation.
method Introducing dual variables to derive optimal allocation conditions, leading to Information-Directed Selection.
result Top-two Thompson sampling attains asymptotic optimality for Gaussian best-arm identification.

Optimizes pure exploration in linear bandits with a new algorithm.

problem Best-arm identification in linear stochastic bandits.
method Developed the first asymptotically optimal algorithm for fixed-confidence pure exploration in linear bandits.
result Avoids the pitfall of a simple but difficult instance and bypasses the need to solve an optimal design problem.

UCB algorithm adapted for large-scale, non-sub-Gaussian problems.

problem Selecting the best alternative from a large set of options with non-sub-Gaussian performance distributions.
method Adapted UCB algorithm for non-sub-Gaussian settings, focusing on sample size and meta-UCB selection.
result UCB algorithms can achieve sample optimality in large-scale, non-sub-Gaussian problems.

Study pure exploration in high-dimensional feature spaces using adaptive embeddings.

problem Overcoming the curse of dimensionality in pure exploration bandits.
method Adaptive embedding of feature representations into lower-dimensional spaces, carefully dealing with model misspecification.
result Sample complexity guarantees that depend on the effective dimension of feature spaces in kernel or neural representations.

We study a specific \textit{combinatorial pure exploration stochastic bandit problem} where the learner aims at finding the set of arms whose means are above a given threshold, up to a given precision, and \textit{for a fixed time horizon}. We propose a parameter-free algorithm based on an original heuristic, and prove…

2016-05-27abs ↗pdf ↗

Study of tangent cones at infinity for algebraic sets.

problem Characterizing algebraic sets based on their tangent cones at infinity.
method Definition and analysis of tangent cones C4,(X)C_{4, \infty}(X) and C5,(X)C_{5,\infty}(X), proving properties and relations.
result Affine linear subspace characterization based on C5,(X)C_{5, \infty}(X)'s dimension.

Paper studies pure virtual twin groups and their automorphisms.

problem Understanding the structure and automorphisms of pure virtual twin groups.
method Analyzes stable isotopy classes of immersed circles on surfaces, extending classical knot theory.
result Proves PVTnPVT_n is an irreducible right-angled Artin group with trivial center and gives its precise presentation.

Study Farrell cohomology for non-orientable surfaces, classifying subgroup conjugacy.

problem Determine the pp-primary component of Farrell cohomology for non-orientable surfaces.
method Classify subgroups of order pp using topological equivalence adapted to surfaces with marked points.
result Determine the pp-primary component of Farrell cohomology for non-orientable surfaces.

We show that there are isometrically nonequivalent Robertson-Walker metrics which have the same set of geodesics. While one of these metrics satisfies the Einstein equations of pure dust without a cosmological constant, all the other describe pure dust with additional energy momentum tensor of cosmological constant typ…

2010-03-07abs ↗pdf ↗

We prove that Kleinian groups whose limit sets are Cantor sets of Hausdorff dimension <1<1 are free. On the other hand we construct for any ε>0ε>0 examples of non-free purely hyperbolic Kleinian groups whose limit set is a Cantor set of Hausdorff dimension <1+ε<1+ε.

2015-05-30abs ↗pdf ↗

We determine the sample complexity of pure exploration bandit problems with multiple good answers. We derive a lower bound using a new game equilibrium argument. We show how continuity and convexity properties of single-answer problems ensures that the Track-and-Stop algorithm has asymptotically optimal sample complexi…

2019-02-09abs ↗pdf ↗

The concept of pure spinor is generalized, giving rise to the notion of pure subspaces, spinorial subspaces associated to isotropic vector subspaces of non-maximal dimension. Several algebraic identities concerning the pure subspaces are proved here, as well as some differential results. Furthermore, the freedom in the…

2013-10-01abs ↗pdf ↗

Characterizes optimal-speed quantum state evolution Hamiltonians.

problem Optimal-speed unitary time evolution of pure and quasi-pure quantum states.
method Construction of the manifold of pure states and isometry with flag manifold, characterization of equigeodesic vectors.
result Hamiltonians generating optimal-speed time evolution are fully characterized by equigeodesic vectors of the flag manifold.

The paper analyzes game theory in convertible contracts during liquidity events.

problem Optimizing payments in convertible contracts during liquidity events.
method Defined a general model for games, showed non-existence of pure strategy Nash equilibria, developed algorithms for computing equilibria.
result Optimum pure strategy Nash equilibria exist when all contracts are of the same type (SAFE).

New algorithm finds high-reward combinatorial sets with fewest pulls.

problem Finding high-reward combinatorial sets with unknown individual arm rewards.
method Successive acceptance and elimination based on combinatorial structure.
result Algorithm requires minimal combinatorial oracle calls, making it practical for large problems.

A spacetime denotes a pure radiation field if its energy momentum tensor represents a situation in which all the energy is transported in one direction with the speed of light. In 1989, Wils and later in 1997 Ludwig and Edgar studied the physical properties of pure radiation metrics, which are conformally related to a …

2017-03-31abs ↗pdf ↗

Employing Morse theory for the global control of monodromy and the method of analytic discs for local extension, we establish a version of the global Hartogs extension theorem in a singular setting: for every domain D of an (n-1)-complete normal complex space X of pure dimension n >= 2 and for every compact set K in D …

2007-04-24abs ↗pdf ↗