Tootfinder

Global Centers and Phase Portraits in Generalized Duffing Oscillators: A Comprehensive Study of the Center-Focus Problem
Gabriel Rond\'on, Nasrin Sadri
https://arxiv.org/abs/2506.07307

Global Centers and Phase Portraits in Generalized Duffing Oscillators: A Comprehensive Study of the Center-Focus Problem
This work presents a comprehensive study of the generalized Duffing oscillator, a fundamental model in nonlinear dynamics described by the system $$ \dot{x} = y, \quad \dot{y} = -αy - εx^m - σx, $$ where $ε\neq 0$ and $m \geq 1$. We focus on the topological classification of phase portraits, the characterization of global centers, and the absence of limit cycles for $α\neq0$. For the linear case ($m = 1$), we establish necessary and sufficient conditions for the origin to be a global cente…

Scalable Spatiotemporal Modeling for Bicycle Count Prediction
Rishikesh Yadav, Alexandra M. Schmidt, Aurelie Labbe, Pratheepa Jeganathan, Luis F. Miranda-Moreno
https://arxiv.org/abs/2506.07582

Scalable Spatiotemporal Modeling for Bicycle Count Prediction
We propose a novel sparse spatiotemporal dynamic generalized linear model for efficient inference and prediction of bicycle count data. Assuming Poisson distributed counts with spacetime-varying rates, we model the log-rate using spatiotemporal intercepts, dynamic temporal covariates, and site-specific effects additively. Spatiotemporal dependence is modeled using a spacetime-varying intercept that evolves smoothly over time with spatially correlated errors, and coefficients of some temporal co…

Results on Colored Tree Properties
Gabriel Day
https://arxiv.org/abs/2507.06977 https://arxiv.org/pdf/2507.06977

Results on Colored Tree Properties
In this paper, we introduce novel variations on several well-known model-theoretic tree properties, and prove several equivalences to known properties. Motivated by the study of generalized indiscernibles, we introduce the notion of the $\calI$-tree property ($\calI$-TP), for an arbitrary Ramsey index structure $\calI$. We focus attention on the colored linear order index structure \textbf{c}, showing that \textbf{c}-TP is equivalent to instability. After introducing \textbf{c}-$\TPi$ and \text…

Enjoying Non-linearity in Multinomial Logistic Bandits
Pierre Boudart (PSL, DI-ENS, Inria), Pierre Gaillard (PSL, DI-ENS, Inria), Alessandro Rudi (PSL, DI-ENS, Inria)
https://arxiv.org/abs/2507.05306

Enjoying Non-linearity in Multinomial Logistic Bandits
We consider the multinomial logistic bandit problem, a variant of generalized linear bandits where a learner interacts with an environment by selecting actions to maximize expected rewards based on probabilistic feedback from multiple possible outcomes. In the binary setting, recent work has focused on understanding the impact of the non-linearity of the logistic model (Faury et al., 2020; Abeille et al., 2021). They introduced a problem-dependent constant $κ_*$, that may be exponentially larg…

The problem of sharp notch in microstructured solids governed by dipolar gradient elasticity
P. A. Gourgiotis, M. D. Sifnaiou, H. G. Georgiadis
https://arxiv.org/abs/2508.03595 …

The problem of sharp notch in microstructured solids governed by dipolar gradient elasticity
In this paper, we deal with the asymptotic problem of a body of infinite extent with a notch (re-entrant corner) under remotely applied plane-strain or anti-plane shear loadings. The problem is formulated within the framework of the Toupin-Mindlin theory of dipolar gradient elasticity. This generalized continuum theory is appropriate to model the response of materials with microstructure. A linear version of the theory results by considering a linear isotropic expression for the strain-energy d…

Model reduction for fully nonlinear stochastic systems
Martin Redmann
https://arxiv.org/abs/2508.02263 https://arxiv.org/pdf/2508.02263

Model reduction for fully nonlinear stochastic systems
This paper presents a novel model order reduction framework tailored for fully nonlinear stochastic dynamics without lifting them to quadratic systems and without using linearization techniques. By directly leveraging structural properties of the nonlinearities -- such as local and one-sided Lipschitz continuity or one-sided linear growth conditions -- the approach defines generalized reachability and observability Gramians through Lyapunov-type differential operators. These Gramians enable pro…

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Generalized Lotka-Volterra systems with quenched random interactions and saturating functional response
Marco Zenari, Francesco Ferraro, Sandro Azaele, Amos Maritan, Samir Suweis
https://arxiv.org/abs/2506.04056

Generalized Lotka-Volterra systems with quenched random interactions and saturating functional response
The generalized Lotka-Volterra (GLV) equations with quenched random interactions have been extensively used to investigate the stability and dynamics of complex ecosystems. However, the standard linear interaction model suffers from pathological unbounded growth, especially under strong cooperation or heterogeneity. This work addresses that limitation by introducing a Monod-type saturating functional response into the GLV framework. Using Dynamical Mean Field Theory, we derive analytical expres…

PGD-based local surrogate models via overlapping domain decomposition: a computational comparison
Marco Discacciati, Ben J. Evans, Matteo Giacomini
https://arxiv.org/abs/2508.01313

PGD-based local surrogate models via overlapping domain decomposition: a computational comparison
An efficient strategy to construct physics-based local surrogate models for parametric linear elliptic problems is presented. The method relies on proper generalized decomposition (PGD) to reduce the dimensionality of the problem and on an overlapping domain decomposition (DD) strategy to decouple the spatial degrees of freedom. In the offline phase, the local surrogate model is computed in a non-intrusive way, exploiting the linearity of the operator and imposing arbitrary Dirichlet conditions…

Generalized Optimal Transport
Andrei Voronin
https://arxiv.org/abs/2507.22422 https://arxiv.org/pdf/2507.22422

Generalized Optimal Transport
Many causal and structural parameters in economics can be identified and estimated by computing the value of an optimization program over all distributions consistent with the model and the data. Existing tools apply when the data is discrete, or when only disjoint marginals of the distribution are identified, which is restrictive in many applications. We develop a general framework that yields sharp bounds on a linear functional of the unknown true distribution under i) an arbitrary collection…

Assessing the Reliability of LLMs Annotations in the Context of Demographic Bias and Model Explanation
Hadi Mohammadi, Tina Shahedi, Pablo Mosteiro, Massimo Poesio, Ayoub Bagheri, Anastasia Giachanou
https://arxiv.org/abs/2507.13138

Assessing the Reliability of LLMs Annotations in the Context of Demographic Bias and Model Explanation
Understanding the sources of variability in annotations is crucial for developing fair NLP systems, especially for tasks like sexism detection where demographic bias is a concern. This study investigates the extent to which annotator demographic features influence labeling decisions compared to text content. Using a Generalized Linear Mixed Model, we quantify this inf luence, finding that while statistically present, demographic factors account for a minor fraction ( 8%) of the observed varianc…

Nonequilibrium transport through the Hubbard dimer
Yaroslav Pavlyukh, Riku Tuovinen
https://arxiv.org/abs/2506.02198 https://arxiv.or…

Nonequilibrium transport through the Hubbard dimer
We apply a computationally efficient approach to study the time- and energy-resolved spectral properties of a two-site Hubbard model using the nonequilibrium Green's function formalism. By employing the iterative generalized Kadanoff-Baym ansatz ($i$GKBA) within a time-linear framework, we avoid the computational cost of solving the full two-time Kadanoff-Baym equations. Spectral information is extracted by coupling the system to multiple narrow-band leads, establishing a direct analogy to phot…

Suppressing excitations in the nonlinear Landau-Zener model
Sebastian Deffner, Steve Campbell
https://arxiv.org/abs/2506.11759 https://

Suppressing excitations in the nonlinear Landau-Zener model
Many complex quantum systems can be described by effectively nonlinear dynamics. While such dynamics have many appealing characteristics, they also make the analysis significantly more involved. This is due to the fact that only a few analytical treatments exist, and that the language of quantum mechanics is built for linear operators. For instance, the very formulation of the quantum adiabatic theorem requires the underlying dynamics to be linear. In this work we show that in a generalized Lan…

Entanglement islands and black hole decay in regular dilaton gravity
Maxim Fitkevich
https://arxiv.org/abs/2507.17933 https://arxiv.org/pdf/2507.17933

Entanglement islands and black hole decay in regular dilaton gravity
We consider a class of two-dimensional dilaton gravity models with linear dilaton vacuum including Callan-Giddings-Harvey-Strominger (CGHS) model as the special case. General thermodynamic properties of black holes in such models are evaluated. We focus on the CGHS model and its modification with regular black holes as empty-space solutions characterized by ever-present finite curvature. We find generalized entanglement entropy blows-up for near-extremal regular black holes considered as remnan…

Multiple-Nanowire Superconducting Quantum Interference Devices: Critical Currents, Symmetries, and Vorticity Stability Regions
Cliff Sun, Alexey Bezryadin
https://arxiv.org/abs/2505.23095

Multiple-Nanowire Superconducting Quantum Interference Devices: Critical Currents, Symmetries, and Vorticity Stability Regions
An ordinary superconducting quantum interference device (SQUID) contains two weak links connected in parallel. We model a multiple-wire SQUID (MW-SQUID), generalized in two ways. First, the number of weak links, which are provided by parallel superconducting nanowires, is larger than two. Second, the current-phase relationship of each nanowire is assumed linear, which is typical for a homogeneous superconducting thin wire. For such MW-SQUIDs, our model predicts that the critical current ($I_c$)…

Exclusive heavy vector meson photoproduction in $pp$ and $pPb$ collisions within the GPD approach: A phenomenological analysis
Ya-Ping Xie, Victor P. Gon\c{c}alves
https://arxiv.org/abs/2507.20448

Exclusive heavy vector meson photoproduction in $pp$ and $pPb$ collisions within the GPD approach: A phenomenological analysis
The exclusive $J/ψ$ and $Υ$ photoproduction in proton - proton ($pp$) and proton - lead ($pPb$) collisions at the LHC energies is investigated using the Generalized Parton Distribution (GDP) approach. Assuming the Goloskokov - Kroll (GK) model, we estimate the corresponding total cross - sections and rapidity distributions considering different parametrizations for the unpolarized gluon distribution of the proton. In particular, we compare the linear predictions, associated with DGLAP evoluti…

A fixed-time stable dynamical model for solving EVLCPs
Yufei Wei, Shiping Lin, Cairong Chen, Dongmei Yu, Deren Han
https://arxiv.org/abs/2507.20652 https://

A fixed-time stable dynamical model for solving EVLCPs
A fixed-time stable dynamical system for solving the extended vertical linear complementarity problem (EVLCP) is developed. The system is based on the reformulation of EVLCP as a special case of a new kind of generalized absolute value equations. Some properties of the new kind of generalized absolute value equations are explored which are useful for developing a fixed-time stable dynamical system for solving it. Without using any smoothing technique, we develop a dynamical system for solving t…

Generalised Harrison transformations and black diholes in Einstein-ModMax
Ana Bokuli\'c, Carlos A. R. Herdeiro
https://arxiv.org/abs/2507.16926 https://

Generalised Harrison transformations and black diholes in Einstein-ModMax
Einstein-Maxwell theory has powerful solution generating techniques which include Harrison transformations in the Ernst formalism. We construct generalized Harrison transformations that preserve the purely magnetic or purely electric sector in Einstein-ModMax (EMM) theory. Thus, they serve as solution generating techniques within these sectors for this model of non-linear electrodynamics minimally coupled to gravity. As an application we rederive several known exact solutions of EMM and a new s…

A studentized permutation test for the treatment effect in individual participant data meta-analysis
Phuc Thien Tran, Long-Hao Xu, Christian R\"over, Tim Friede
https://arxiv.org/abs/2505.24774

A studentized permutation test for the treatment effect in individual participant data meta-analysis
Meta-analysis is a well-established tool used to combine data from several independent studies, each of which usually compares the effect of an experimental treatment with a control group. While meta-analyses are often performed using aggregated study summaries, they may also be conducted using individual participant data (IPD). Classical meta-analysis models may be generalized to handle continuous IPD by formulating them within a linear mixed model framework. IPD meta-analyses are commonly bas…

Model-robust standardization in stepped wedge designs
Xi Fang, Xueqi Wang, Patrick J. Heagerty, Bingkai Wang, Fan Li
https://arxiv.org/abs/2507.17190 https://

Model-robust standardization in stepped wedge designs
Stepped-wedge cluster-randomized trials (SW-CRTs) are widely used in healthcare and implementation science, providing an ethical advantage by ensuring all clusters eventually receive the intervention. The staggered rollout of treatment introduces complexities in defining and estimating treatment effect estimands, particularly under informative sizes. Traditional model-based methods, including generalized estimating equations (GEE) and linear mixed models (LMM), produce estimates that depend on …

Simultaneous Estimation and Model Choice for Big Discrete Time-to-Event Data with Additive Predictors
Benjamin M\"uller, Nikolaus Umlauf, Johannes Seiler, Kenneth Harttgen, Stefan Lang
https://arxiv.org/abs/2507.08099

Simultaneous Estimation and Model Choice for Big Discrete Time-to-Event Data with Additive Predictors
Discrete-time hazard models are widely used when event times are measured in intervals or are not precisely observed. While these models can be estimated using standard generalized linear model techniques, they rely on extensive data augmentation, making estimation computationally demanding in high-dimensional settings. In this paper, we demonstrate how the recently proposed Batchwise Backfitting algorithm, a general framework for scalable estimation and variable selection in distributional reg…

Data-driven balanced truncation for second-order systems with generalized proportional damping
Sean Reiter, Steffen W. R. Werner
https://arxiv.org/abs/2506.10118

Data-driven balanced truncation for second-order systems with generalized proportional damping
Structured reduced-order modeling is a central component in the computer-aided design of control systems in which cheap-to-evaluate low-dimensional models with physically meaningful internal structures are computed. In this work, we develop a new approach for the structured data-driven surrogate modeling of linear dynamical systems described by second-order time derivatives via balanced truncation model-order reduction. The proposed method is a data-driven reformulation of position-velocity bal…