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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 harmonic-mean

The paper studies constant harmonic mean curvature surfaces in Schwarzschild spaces, proving they foliate the space.

problem Investigating constant harmonic mean curvature surfaces in Schwarzschild spaces.
method Volume-preserving harmonic mean curvature flow in asymptotically Schwarzschild spaces.
result These surfaces form a foliation of the space outside a large ball.

Paper extends foliation results in higher dimensions for Schwarzschild spaces.

problem Existence of foliations by constant harmonic mean curvature hypersurfaces in asymptotically Schwarzschild manifolds.
method Generalization to higher dimensions, proving existence under arbitrary dimensionality.
result Existence of foliations by constant harmonic mean curvature hypersurfaces in asymptotically Schwarzschild manifolds of arbitrary dimension.

This paper explores the harmonic mean of implied volatility and its relation to local volatility.

problem Understanding the relationship between implied volatility and local volatility.
method Investigates the harmonic mean of a positive function for any fixed maturity, linking it to Fukasawa's invertible map.
result The short-dated implied volatility approaches the arithmetic mean of the local volatility in a new coordinate system.

Consider oriented surfaces immersed in R3.\mathbb R^3. Associated to them, here are studied pairs of transversal foliations with singularities, defined on the Elliptic region, where the Gaussian curvature K\mathcal K, given by the product of the principal curvatures k1,k2k_1, k_2 is positive. The leaves of the foliations …

2003-02-18abs ↗pdf ↗

In this article, we will use the harmonic mean curvature flow to prove a new class of Alexandrov-Fenchel type inequalities for strictly convex hypersurfaces in hyperbolic space in terms of total curvature, which is the integral of Gaussian curvature on the hypersurface. We will also use the harmonic mean curvature flow…

2019-03-14abs ↗pdf ↗

This paper gives some examples of hypersurfaces φt(Mn)φ_t(M^n) evolving in time with speed determined by functions of the normal curvatures in an (n+1)(n+1)-dimensional hyperbolic manifold; we emphasize the case of flow by harmonic mean curvature. The examples converge to a totally geodesic submanifold of any dimension from 1…

2009-04-08abs ↗pdf ↗

In this note, using the spinorial description of SU(3)SU(3) and G2G_2-structures obtained recently by other authors, we give necessary and sufficient conditions for harmonicity of above mentioned structures. We describe obtained results on appropriate homogeneous spaces. Here, harmonicity means harmonicity of the unique s…

2019-01-17abs ↗pdf ↗

Paper introduces a new performance metric for class imbalance datasets.

problem Challenges in selecting and comparing models for imbalanced datasets.
method Proposes a new performance measure based on the harmonic mean of Recall and Selectivity normalized in class labels.
result The proposed measure is less sensitive to changes in the majority class and more sensitive to changes in the minority class.

A coupling method and an analytic one allow us to prove new lower bounds for the spectral gap of reversible diffusions on compact manifolds. Those bounds are based on the a notion of curvature of the diffusion, like the coarse Ricci curvature or the Bakry--Emery curvature-dimension inequalities. We show that when this …

2011-05-30abs ↗pdf ↗

Zero-shot understanding of accidents from surveillance videos using vision-language models

problem Accident understanding from surveillance videos
method Three-stage pipeline with vision-language similarity, metadata-driven multi-prompt reasoning, and entropy-gated pairwise adjudicator
result Substantial improvement in harmonic-mean score over baseline

We consider a compact, star-shaped, mean convex hypersurface Σ2R3Σ^2\subset \mathbb{R}^3. We prove that in some cases the flow exists until it shrinks to a point in a spherical manner, which is very typical for convex surfaces as well (see \cite{An1}). We also prove that in the case we have a surface of revolution which …

2008-06-10abs ↗pdf ↗

Study Hamiltonian stationary Lagrangian surfaces in complex space forms.

problem Characterize Lagrangian surfaces with harmonic mean curvature in complex space forms.
method Analyze surfaces with constant and harmonic mean curvature, using second fundamental form parallelism and Gaussian curvature constancy.
result Complete classification of Lagrangian surfaces with harmonic mean curvature and constant Gaussian curvature.

We show that any strictly mean convex translator of dimension n3n\geq 3 which admits a cylindrical estimate and a corresponding gradient estimate is rotationally symmetric. As a consequence, we deduce that any translating solution of the mean curvature flow which arises as a blow-up limit of a two-convex mean curvature…

2016-05-31abs ↗pdf ↗

This note displays an interesting phenomenon for percentiles of independent but non-identical random variables. Let X1,,XnX_1,\cdots,X_n be independent random variables obeying non-identical continuous distributions and X(1)X(n)X^{(1)}\geq \cdots\geq X^{(n)} be the corresponding order statistics. For any p(0,1)p\in(0,1), we investig…

2018-08-24abs ↗pdf ↗

This paper provides new insight into maximizing F1 scores in the context of binary classification and also in the context of multilabel classification. The harmonic mean of precision and recall, F1 score is widely used to measure the success of a binary classifier when one class is rare. Micro average, macro average, a…

2014-02-08abs ↗pdf ↗

This work improves understanding of symmetrizing Bregman divergences on positive definite matrices.

problem Understanding which mean to use for symmetrizing Bregman divergences on positive definite matrices.
method Axiomatic definition of mean functionals and variational principles over the cone of positive definite matrices.
result The arithmetic mean is canonical for forward symmetrization, and the arithmetic, log-Euclidean, and harmonic means for reverse symmetrization.

When investors have heterogeneous attitudes towards risk, it is reasonable to assume that each investor has a pricing kernel, and that these individual pricing kernels are aggregated to form a market pricing kernel. The various investors are then buyers or sellers depending on how their individual pricing kernels compa…

2013-01-14abs ↗pdf ↗

New estimator reduces risk in slate bandits by leveraging Bayes risk criterion.

problem Evaluating slate policies using logged data when policies factorize over slots.
method Developed a new estimator using a control variate approach, showing risk improvement over existing methods.
result The new estimator has lower risk than the pseudoinverse estimator in slate bandit problems.

A new method for distributed PCA using matrix β-mean.

problem Efficiently aggregating PCA results across multiple machines with reduced computational overhead.
method Proposes a novel DPCA method that incorporates eigenvalue information using the matrix β-mean.
result The matrix β-mean method improves robustness and stability of eigenvector ordering.

Paper decomposes C-index to analyze survival prediction model performance.

problem Evaluating the performance of survival prediction models.
method Decomposes C-index into two weighted quantities: ranking observed vs. other events and observed vs. censored cases.
result Deep learning models outperform classical models in ranking observed events, leading to better C-index stability.

Paper optimizes federated PCA for covariance estimation under privacy constraints.

problem Privacy-preserving covariance estimation in federated learning.
method Federated PCA, matrix version of van Trees' inequality, three-layer spectral decomposition.
result Optimal rates of convergence for central server's estimation, robust to inconsistent local estimators.

The paper introduces a new method for estimating optimal policies in dynamic treatment regimes using information geometry.

problem Estimating optimal policies in dynamic treatment regimes.
method Minimum information divergence method based on γγ-power divergence.
result The γγ-power divergence method effectively seeks the optimal policy by vanishing the divergence between policy-equivalent Q-functions.

LETS-GZSL tackles GZSL for time series classification, achieving high accuracy.

problem Recognizing unseen classes from time series data when only seen examples are labeled.
method Embedding-based approach combined with attribute vectors.
result Achieves a harmonic mean of at least 55% on most UCR datasets.