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cb70ab375662576bd1ac5aaf16b3fca4-AuthorFeedback.pdf

Neural Information Processing Systems

We thank all reviewers for the time they invested to review this paper and share their insights. We have conducted experiments on real-world data, yet could not include them within page limits. Publication of the algorithm in an implemented code (e.g. Java as stated in Line 304). The pseudocodes are given below.


Quantum Neural Networks for Propensity Score Estimation and Survival Analysis in Observational Biomedical Studies

Novák, Vojtěch, Zelinka, Ivan, Přibylová, Lenka, Martínek, Lubomír

arXiv.org Machine Learning

This study investigates the application of quantum neural networks (QNNs) for propensity score estimation to address selection bias in comparing survival outcomes between laparoscopic and open surgical techniques in a cohort of 1177 colorectal carcinoma patients treated at University Hospital Ostrava (2001-2009). Using a dataset with 77 variables, including patient demographics and tumor characteristics, we developed QNN-based propensity score models focusing on four key covariates (Age, Sex, Stage, BMI). The QNN architecture employed a linear ZFeatureMap for data encoding, a SummedPaulis operator for predictions, and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) for robust, gradient-free optimization in noisy quantum environments. Variance regularization was integrated to mitigate quantum measurement noise, with simulations conducted under exact, sampling (1024 shots), and noisy hardware (FakeManhattanV2) conditions. QNNs, particularly with simulated hardware noise, outperformed classical logistic regression and gradient boosted machines in small samples (AUC up to 0.750 for n=100), with noise modeling enhancing predictive stability. Propensity score matching and weighting, optimized via genetic matching and matching weights, achieved covariate balance with standardized mean differences of 0.0849 and 0.0869, respectively. Survival analyses using Kaplan-Meier estimation, Cox proportional hazards, and Aalen additive regression revealed no significant survival differences post-adjustment (p-values 0.287-0.851), indicating confounding bias in unadjusted outcomes. These results highlight QNNs' potential, enhanced by CMA-ES and noise-aware strategies, to improve causal inference in biomedical research, particularly for small-sample, high-dimensional datasets.


An entropy-optimal path to humble AI

Bassetti, Davide, Pospíšil, Lukáš, Groom, Michael, O'Kane, Terence J., Horenko, Illia

arXiv.org Machine Learning

Progress of AI has led to a creation of very successful, but by no means humble models and tools, especially regarding (i) the huge and further exploding costs and resources they demand, and (ii) the over-confidence of these tools with the answers they provide. Here we introduce a novel mathematical framework for a non-equilibrium entropy-optimizing reformulation of Boltzmann machines based on the exact law of total probability. It results in the highly-performant, but much cheaper, gradient-descent-free learning framework with mathematically-justified existence and uniqueness criteria, and answer confidence/reliability measures. Comparisons to state-of-the-art AI tools in terms of performance, cost and the model descriptor lengths on a set of synthetic problems with varying complexity reveal that the proposed method results in more performant and slim models, with the descriptor lengths being very close to the intrinsic complexity scaling bounds for the underlying problems. Applying this framework to historical climate data results in models with systematically higher prediction skills for the onsets of La Niña and El Niño climate phenomena, requiring just few years of climate data for training - a small fraction of what is necessary for contemporary climate prediction tools.


ReLCP: Scalable Complementarity-Based Collision Resolution for Smooth Rigid Bodies

Palmer, Bryce, Aktulga, Hasan Metin, Gao, Tong

arXiv.org Artificial Intelligence

We present a complementarity-based collision resolution algorithm for smooth, non-spherical, rigid bodies. Unlike discrete surface representation approaches, which approximate surfaces using discrete elements (e.g., tessellations or sub-spheres) with constraints between nearby faces, edges, nodes, or sub-objects, our algorithm solves a recursively generated linear complementarity problem (ReLCP) to adaptively identify potential collision locations during the collision resolution procedure. Despite adaptively and in contrast to Newton-esque schemes, we prove conditions under which the resulting solution exists and the center of mass translational and rotational dynamics are unique. Because increasing the surface resolution in discrete representation methods necessitates subdividing geometry into finer elements--leading to a super-linear increase in the number of collision constraints--these approaches scale poorly with increased surface resolution. In contrast, our adaptive ReLCP framework begins with a single constraint per pair of nearby bodies and introduces new constraints only when unconstrained motion would lead to overlap, circumventing the oversampling required by discrete methods. By requiring one to two orders of magnitude fewer collision constraints to achieve the same surface resolution, we observe 10-100x speedup in densely packed applications. We validate our ReLCP method against multisphere and single-constraint methods, comparing convergence in a two-ellipsoid collision test, scalability and performance in a compacting ellipsoid suspension and growing bacterial colony, and stability in a taut chainmail network, highlighting our ability to achieve high-fidelity surface representations without su ff ering from poor scalability or artificial surface roughness. Keywords: Rigid body dynamics, Nonsmooth dynamics, Linear complementarity problem, Collision resolution, ReLCP 1. Introduction The simulation of collision and contact dynamics in rigid and flexible body systems has a rich and extensive history in scientific computing, engineering, and computer graphics. Methods for managing frictional contact and resolving collisions can be broadly categorized into three types: piecewise-smooth, smooth (penalty-based), and nonsmooth (complementarity-based) methods. Piecewise-smooth approaches focus on identifying the precise times and locations of collision events, applying instantaneous impulses to uphold the conservation of momentum. While these methods are conceptually straightforward and lend themselves well to analytical treatment, they are rarely employed in large-scale simulations.


Fast and close Shannon entropy approximation

Horenko, Illia, Bassetti, Davide, Pospíšil, Lukáš

arXiv.org Artificial Intelligence

Shannon entropy (SE) and its quantum mechanical analogue von Neumann entropy are key components in many tools used in physics, information theory, machine learning (ML) and quantum computing. Besides of the significant amounts of SE computations required in these fields, the singularity of the SE gradient is one of the central mathematical reason inducing the high cost, frequently low robustness and slow convergence of such tools. Here we propose the Fast Entropy Approximation (FEA) - a non-singular rational approximation of Shannon entropy and its gradient that achieves a mean absolute error of $10^{-3}$, which is approximately $20$ times lower than comparable state-of-the-art methods. FEA allows around $50\%$ faster computation, requiring only $5$ to $6$ elementary computational operations, as compared to tens of elementary operations behind the fastest entropy computation algorithms with table look-ups, bitshifts, or series approximations. On a set of common benchmarks for the feature selection problem in machine learning, we show that the combined effect of fewer elementary operations, low approximation error, and a non-singular gradient allows significantly better model quality and enables ML feature extraction that is two to three orders of magnitude faster and computationally cheaper when incorporating FEA into AI tools.