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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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69138206275 · May 202619922001200920172026
48 results for discrete mechanics

In this paper we propose a process of lagrangian reduction and reconstruction for nonholonomic discrete mechanical systems where the action of a continuous symmetry group makes the configuration space a principal bundle. The result of the reduction process is a discrete dynamical system that we call the discrete reduce…

2010-04-24abs ↗pdf ↗

This work extends reduction processes for nonholonomic discrete mechanical systems.

problem Nonholonomic discrete mechanical systems and their reductions.
method Introduces a category LDPdLDP_d of discrete-time dynamical systems and a two-stage reduction process.
result Two-stage reduction process produces systems isomorphic to one-stage reduction.

Study preserves symplectic structure in forced discrete mechanical systems.

problem Preserving symplectic structure in forced discrete mechanical systems.
method Analyzes a specific type of forced discrete mechanical system (Q,Ld,fd)(Q,L_d,f_d), preserving a symplectic structure on QimesQQ imes Q.
result The preserved symplectic structure can be seen as Marsden-Weinstein reduction of the canonical symplectic structure.

The paper analyzes errors in mechanical systems with external forces.

problem Error analysis of mechanical systems with external forces.
method Analysis of variational integrators with contact order rr for discrete mechanical systems.
result The contact order of the integrator is the same as the contact order of the original systems.

In this paper, we introduce local expressions for discrete Mechanics. To apply our results simultaneously to several interesting cases, we derive these local expressions in the framework of Lie groupoids, following the program proposed by Alan Weinstein in [19]. To do this, we will need some results on the geometry of …

2013-03-17abs ↗pdf ↗

In this work we introduce a category of discrete Lagrange--Poincare systems LP_d and study some of its properties. In particular, we show that the discrete mechanical systems and the discrete mechanical systems obtained by the Lagrangian reduction of symmetric discrete mechanical systems are objects in LP_d. We introdu…

2015-11-20abs ↗pdf ↗

The paper improves privacy accounting for discrete-valued mechanisms and the subsampled Gaussian mechanism.

problem Improving the accuracy and efficiency of differential privacy accounting for discrete outputs.
method Uses fast Fourier transform (FFT) for rigorous error analysis and accounting of privacy loss.
result Provides strict lower and upper bounds for (ε,δ)(\varepsilon,δ)-values, demonstrating up to 75% reduction in noise variance.

The paper introduces discrete Dirac structures for mechanics, simplifying dynamics.

problem Formulating discrete mechanics with constraints.
method Developed (±)(\pm)-discrete Dirac structures and induced Dirac structures.
result Discrete Lagrange--Dirac systems are equivalent to (±)(\pm)-discrete Lagrange--d'Alembert equations.

We develop a geometric version of the inverse problem of the calculus of variations for discrete mechanics and constrained discrete mechanics. The geometric approach consists of using suitable Lagrangian and isotropic submanifolds. We also provide a transition between the discrete and the continuous problems and propos…

2017-08-14abs ↗pdf ↗

New methods test discrete distributions faster with local privacy constraints.

problem Testing discrete distributions under local differential privacy constraints.
method Efficient randomized algorithms and test procedures, both non-interactive and interactive.
result Faster separation rates in interactive privacy mechanisms.

The purpose of this paper is to describe geometrically discrete Lagrangian and Hamiltonian Mechanics on Lie groupoids. From a variational principle we derive the discrete Euler-Lagrange equations and we introduce a symplectic 2-section, which is preserved by the Lagrange evolution operator. In terms of the discrete Leg…

2005-06-15abs ↗pdf ↗

Connections on principal bundles play a fundamental role in expressing the equations of motion for mechanical systems with symmetry in an intrinsic fashion. A discrete theory of connections on principal bundles is constructed by introducing the discrete analogue of the Atiyah sequence, with a connection corresponding t…

2005-08-18abs ↗pdf ↗

The collection and analysis of user data drives improvements in the app and web ecosystems, but comes with risks to privacy. This paper examines discrete distribution estimation under local privacy, a setting wherein service providers can learn the distribution of a categorical statistic of interest without collecting …

2016-02-24abs ↗pdf ↗

New privacy mechanism for user-level discrete distributions with reduced penalty.

problem Achieving privacy for all items of a single user in practical applications.
method Study of learning discrete distributions with user-level differential privacy, proposing a new mechanism with reduced privacy penalty.
result Proposed mechanism reduces privacy penalty to ildeO(k/(mα2)+k/mεα) ilde{\mathcal{O}}(k/(mα^2) + k/\sqrt{m}εα), significantly smaller than standard mechanisms.

We address the problem of constructing numerical integrators for nonholonomic Lagrangian systems that enjoy appropriate discrete versions of the geometric properties of the continuous flow, including the preservation of energy. Building on previous work on time-dependent discrete mechanics, our approach is based on a d…

2002-09-24abs ↗pdf ↗

Perceptrons have been known for a long time as a promising tool within the neural networks theory. The analytical treatment for a special class of perceptrons started in seminal work of Gardner \cite{Gar88}. Techniques initially employed to characterize perceptrons relied on a statistical mechanics approach. Many of su…

2013-06-17abs ↗pdf ↗

Defines hybrid systems on principal bundles and studies impact effects.

problem Understanding impact effects in hybrid mechanical systems.
method Defines hybrid systems on principal bundles, studies underlying geometry, and finds conditions for impact preservation.
result Conditions for preservation of both exterior and interior impacts by mechanical connections.

CANDI solves the gap between continuous and discrete diffusion models for text generation.

problem Underperformance of continuous diffusion models in discrete data domains.
method Introduces token identifiability and a hybrid framework (CANDI) to decouple discrete and continuous corruption.
result CANDI successfully avoids temporal dissonance, enabling continuous diffusion benefits for discrete spaces.

This paper presents a geometric-variational approach to continuous and discrete mechanics and field theories. Using multisymplectic geometry, we show that the existence of the fundamental geometric structures as well as their preservation along solutions can be obtained directly from the variational principle. In parti…

1998-07-15abs ↗pdf ↗

A closed linkage mechanism in three-dimensional space is an object comprising rigid bodies connected with hinges in a circular form like a rosary. Such linkages include Bricard6R and Bennett4R. To design such a closed linkage, it is necessary to solve a high-degree algebraic equation, which is generally difficult. In t…

2019-09-05abs ↗pdf ↗

Robust Bayesian inference improves model performance on discrete data.

problem Misspecification of discrete-valued models leads to poor inference and prediction.
method Total Variation Distance (TVD) for discrepancy, efficient estimator and inference method.
result Our approach significantly improves predictive performance on various data.

Geometric integrator preserves coadjoint orbits in dissipative systems.

problem Preserving coadjoint orbits in dissipative mechanical systems.
method Adapted discrete variational integrators for forced Euler-Poincaré and Lie-Poisson systems.
result Preserves coadjoint orbits exactly, improving over general-purpose methods.

Study local differential privacy methods for estimating power sums of discrete distributions.

problem Estimating non-linear functionals of discrete distributions under local differential privacy constraints.
method Interactive and non-interactive mechanisms for estimating power sums, with lower bounds provided.
result Achieves faster rates of estimation under certain conditions.

In this paper, we propose a geometric integrator for nonholonomic mechanical systems. It can be applied to discrete Lagrangian systems specified through a discrete Lagrangian defined on QxQ, where Q is the configuration manifold, and a (generally nonintegrable) distribution in TQ. In the proposed method, a discretizati…

2007-09-10abs ↗pdf ↗

Unified framework extends adjoint Schrödinger bridge sampler to discrete spaces.

problem Challenges in learning discrete neural samplers due to gradients and combinatorial complexity.
method Introduces discrete ASBS, a unified framework that extends adjoint Schrödinger bridge sampler to discrete spaces.
result Empirically, discrete ASBS achieves competitive sample quality with significant advantages in training efficiency and scalability.

Optimal weights improve particle-based approximations of discrete distributions.

problem Improving particle-based approximations of discrete distributions.
method Proving optimality of weights and showing how to compute them efficiently.
result Optimal weights can be computed from existing particle-based methods without extra costs.

New sampler tackles complex discrete energy landscapes efficiently.

problem Stagnation in gradient-based discrete samplers for non-convex settings.
method DREXEL sampler with Replica Exchange and Adjusted Metropolis.
result Proves samplers satisfy detailed balance and converge to target distribution.

A system for federated learning with private data, adding discrete Gaussian noise and secure aggregation.

problem Training models on private data distributed across devices while ensuring privacy.
method Discretizes data, adds discrete Gaussian noise, and uses secure aggregation to protect privacy.
result Matches the accuracy of central differential privacy with less than 16 bits of precision per value.

This paper presents a variational and multisymplectic formulation of both compressible and incompressible models of continuum mechanics on general Riemannian manifolds. A general formalism is developed for non-relativistic first-order multisymplectic field theories with constraints, such as the incompressibility constr…

2000-05-03abs ↗pdf ↗

We briefly review the notion of second order constrained (continuous) system (SOCS) and then propose a discrete time counterpart of it, which we naturally call discrete second order constrained system (DSOCS). To illustrate and test numerically our model, we construct certain integrators that simulate the evolution of …

2013-12-06abs ↗pdf ↗

Survey explores cohomology's roles in applied math and sciences.

problem Understanding cohomology's role in solving differential equations.
method Examining differential complexes and structure-preserving discretizations.
result Various fundamental concepts in mechanics are formulated using differential complexes.

We propose a method to classify the causal relationship between two discrete variables given only the joint distribution of the variables, acknowledging that the method is subject to an inherent baseline error. We assume that the causal system is acyclicity, but we do allow for hidden common causes. Our algorithm presu…

2016-11-04abs ↗pdf ↗

Neural Ordinary Differential Equation (Neural ODE) has been proposed as a continuous approximation to the ResNet architecture. Some commonly used regularization mechanisms in discrete neural networks (e.g. dropout, Gaussian noise) are missing in current Neural ODE networks. In this paper, we propose a new continuous ne…

2019-06-05abs ↗pdf ↗

Locally-verifiable conditions ensure exactness of spline discrete de Rham complex.

problem Ensuring cohomological equivalence of spline discrete complex to continuous de Rham complex.
method Theoretical analysis and locally-verifiable sufficient conditions for exactness.
result Locally-verifiable conditions guarantee exactness of hierarchical B-spline discrete de Rham complex.