Papers

We establish quantitative stability for the reciprocal-sum isoperimetric inequality for the first $d$ nonzero Neumann eigenvalues, recently proved by He, Li, and Tang. We prove that for bounded Lipschitz domains in $\mathbb{R}^d$, the reciprocal-sum deficit controls quadratically both the normalized eigenvalue displacements and the Fraenkel asymmetry, while controlling the displacement of the eigenvalue sum linearly. A further result shows that the classical Szegő–Weinberger deficit controls both the gap between the first two nonzero eigenvalues and the full width of the first eigenvalue cluster. Nearly spherical perturbations demonstrate that all the stability exponents are optimal. In dimension two, the same matrix method yields improved constraints on the joint spectral image of the first two nonzero eigenvalues.

We provide a simple and tight characterization of the types of inexact score oracle access that permit sampling with vanishing total variation bias, for a standard, well-behaved target family. Our main result shows that any weaker error than the sub-Gaussian assumption used by [YW26] rules out the tractability of unbiased sampling. This strengthens the conclusion of [CCSW26] to be algorithm-agnostic, and to hold for a wider range of error assumptions.

We study the Minkowski geometry of finite-level sets of Gaussian rationals defined by the lengths of their Hurwitz continued fraction expansions. For each $m\geq 1$, let $H_m$ be the set of points in the fundamental square whose Hurwitz continued fraction expansions have length exactly $m$. We also introduce the relaxed recursive sets defined by $G_0=\{0\}$ and $$G_m=\Big\{\frac{1}{u+v}: u \in\mathbb{Z}[i],\ v\in G_{m-1},\ |u+v|>1 \Big\}.$$ We prove that for every $m\geq 1$, $$\dim_{\rm M} H_m=\dim_{\rm M} G_m=1.$$ We further determine the critical one-dimensional Minkowski content of these sets. We have ${\mathcal M}^1(H_1)={\mathcal M}^1(G_1)=4\pi\log(1+\sqrt{2})$, whereas ${\mathcal M}^1(H_m)={\mathcal M}^1(G_m)=\infty$ for every $m\geq 2$.

Consider the Sachdev-Ye-Kitaev model with $N$ Majorana fermions and interaction order $q$. For even $4\leq q\ll \sqrt{N}$, we present a microscopic framework that determines the free energy limit at every fixed inverse temperature $\beta>0$. In particular, this gives the first rigorous derivation of the Schwinger-Dyson thermodynamics of the model. For all even $q\in \{4,6,...,N-4\}$, we further determine the asymptotic location of the largest eigenvalue, which answers a question posed by Feng-Tian-Wei \cite{FengTianWei1}. Consequently, we obtained the free energy limit along every sequence $\beta\equiv \beta_N\to\infty$.

Structural reliability analysis often requires estimating small failure probabilities under uncertainty, a task for which direct Monte Carlo simulation becomes inefficient because failure observations are scarce. Quantum amplitude estimation offers a potential quadratic improvement in query complexity for bounded expectation estimation, but practical iterative formulations require reliable inference from finite, amplified measurement data. This paper develops a Bayesian sequential formulation of iterative quantum amplitude estimation for rare-event structural failure probability estimation. Structural failure is represented as a binary indicator over a finite stochastic ensemble and encoded through a lookup-table oracle, allowing the failure probability to be treated as a quantum amplitude. Measurement outcomes collected at different Grover depths are assimilated through Bayesian updating over the amplitude angle, yielding posterior estimates, credible intervals, and uncertainty-aware convergence diagnostics. The framework is evaluated on stochastic finite-element benchmark problems, including a one-dimensional bar and an L-bracket with stress concentration. The results show that amplitude amplification converts rare failure events into measurable success probabilities, enabling substantially lower estimation errors than direct Monte Carlo simulation under the same idealized oracle-query budget. The Bayesian formulation achieves point-estimation accuracy comparable to maximum-likelihood IQAE while additionally providing posterior uncertainty quantification, credible intervals, and transparent convergence assessment. The study demonstrates Bayesian IQAE as a statistically interpretable proof-of-concept for quantum-assisted rare-event reliability analysis, while relying on idealized oracle access.

This three-part series establishes a parameter-free, topological classification of multi-field instability in granular continua, extending Maxwell's rigidity count to dynamic, non-equilibrium processes. Part 1 (Foundations): a discrete Volumetric-Mechanical-Configurational (VMC) contact formulation maps contact-scale topology to macroscopic multiphysics coupling. A Parity Theorem, $\det(\mathsf{L})=(-1)^N\det(\mathsf{L})$, forces a structural null-mode for every odd channel count $N$, creating "Gateway" layers of broken time-reversal symmetry; once the basis-invariant Gateway number $\mathcal{G}_{\rm inv}\geq 1$, gyroscopic pumping drives non-modal transient amplification along the null direction. Part 2 (analytical, 1-D spin chains): the minimal Gateway is the $N=3$ VMC contact, whose skew block $\mathsf{L}\in\mathfrak{so}(3)$ carries a persistent zero eigenvalue and an unresisted configurational drift that operates even without friction. In an acyclic chain (first Betti number $\beta_1=0$) this isolates dilatancy; closed-form solutions give secular drift for $N=3$ and harmonic confinement for $N=4$. Part 3 (numerical upscaling): quad-precision integration of tridiagonal skew-symmetric Onsager chains ($N=3$ to $50$) confirms the contrast between odd-$N$ secular drift and even-$N$ confinement on invariant tori, with even-chain frequencies scaling as $|\lambda_{\min}^{\rm even}|\sim\gamma\pi/N$. VMC channels map to measurable DEM observables, enabling parameter-free evaluation of $\mathcal{G}$ and four falsifiable oedometer protocols.

The field of moduli of a variety $X$ over an algebraically closed field $K$ is defined as the fixed field of those automorphisms $\sigma$ of $K$ for which $X\cong X^{\sigma}$. A fundamental question is under what conditions a variety admits a model over its field of moduli. We investigate this problem for curves of genus $6$, by considering the stratification of the moduli space $M_6$.

Let $X$ be a compact Kähler manifold. In prior work, we constructed diffeological moduli stacks of Higgs and flat bundles on $X$, related by extension completion of smooth harmonic families. Here, we develop the relative analytic theory. On Sobolev completions over arbitrary plots, we prove that every smooth stable Higgs family satisfying the numerical conditions admits a global smooth harmonic metric. Fixing a Hermitian–Einstein determinant metric removes scalar freedom, and then elliptic regularity and normalized gluing yield plotwise smoothness. The theorem holds at every finite parameter regularity $C^d$ and on reduced singular parameter spaces with ambient extensions. For a Higgs deformation $\eta$, the normalized metric variation satisfies $L_hs=-\mathcal S_h(\eta)$ and $s=-G_h\mathcal S_h(\eta)$ up to an independent rank-one determinant term for $\mathrm{GL}_r$. This computes the plotwise differential and recovers the classical comparison. Locally split, constant-type polystable families admit smooth harmonic metrics. Real-analytic examples show general polystable families may have neither continuous harmonic metrics nor relative harmonic filtrations and may lie outside every $C^d$ extension-generated locus. In one example a singular harmonic reduction produces a continuous adjoint Higgs field and a flat family with semisimple slices. This defines a weak $C^0$ operator-level harmonic mediator, strictly larger than the metric-regular one, whose endpoint images after finite extension completion and stackification satisfy $\mathscr M_{\mathrm{Dol},0}^{\mathrm{wk}\mathcal H}(X)\simeq\mathscr M_{\mathrm{dR},0}^{\mathrm{wk}\mathcal H}(X)$. We characterize the extension-generated stack by relative harmonic filtrations, develop their obstruction theory, analyze the loss of extension data under heat flow, and construct the smooth Hodge $\lambda$-family on the stable locus.

We prove a refinement of a recent structural result in topological dynamics due to Glasscock, Koutsogiannis, Le, Moreira, Richter, and Robertson, who showed that in a minimal system, polynomial return-times differ by non-piecewise syndetic sets from those in its maximal infinite-step pronilfactor. In particular, we prove that the infinite-step pronilfactor can be replaced by the maximal $k$-step pronilfactor of the system, where $k$ depends only on the given polynomials, with $k-1$ being equal to the Host-Kra complexity of the polynomials.

We study several probabilistic questions concerning the digits of $s(n)$, the sum of proper divisors of an integer $n$. In particular, we show that $s(n)$ obeys Benford's law with respect to logarithmic density. Moreover, we show that, for every function $k(x) \rightarrow \infty$, almost all integers $n \leq x$ have every decimal digit occurring among the first $k(x)$ digits and the last $k(x)$ digits of $s(n)$. We also present an upper bound for the number of composite integers $n$ up to $x$ for which $s(n)$ is missing at least one digit in its decimal expansion. This is in contrast with the main result of a recent paper of Benli, Cesana, Dartyge, Dombrowsky, and Thompson, in which the inputs $n$ were not required to be composite. It turns out that the primes make a substantial contribution to the preimage set $s^{-1}(\mathcal{A})$, where $\mathcal{A}$ is a set of integers with missing digits. Our result for composite $n$ shows that the count is much smaller when prime inputs are excluded.

In this work, we explore a model of immune response in the skeletal muscle of the mdx mouse, the preferred animal model for studying Duchenne Muscular Dystrophy. The system studied is based on existing literature and describes the reaction of the tissue, and of the immune cells within it, to external damage, focusing specifically on the regeneration process. This work extends the analysis conducted by the authors of the original paper, highlighting interesting dynamical properties of the system, particularly in terms of longterm behavior and dependence on initial conditions. A modification is then introduced to the original equations, incorporating a diffusion term for immune cells. The dynamics of the system is numerically investigated in both the one-dimensional and two-dimensional cases. Specifically, we investigate the effect of diffusion under various boundary conditions, and the system's response to localized damage.

In this paper we first introduce a new class of derivative operators, termed $g$-derivative operators, which unifies the $q$-derivative, $(p,q)$-derivative and $(\alpha,\beta,\gamma)$-derivative operators, even classical derivative in the literature. Based on this generalized framework, we define two novel function classes, specifically $g$-starlike functions and $g$-convex functions. Further, we employ the subordination principle of analytic functions to conduct the coefficient estimations for such function classes, and subsequently derive the bounds for the corresponding Fekete-Szegö inequality, Toeplitz determinants and Hankel determinants.

We study connections between discrete probability distributions and the statistical mechanics of small systems. Using probability generating functions, we develop the theory of power series, infinitely divisible, and scalable distributions of non-negative integer-valued random variables, and introduce the class of Markovian distributions that arise naturally in stationary solutions of birth-death processes and in scalable infinitely divisible distributions. These results are applied to the grand canonical ensemble description in statistical mechanics: the infinite divisibility leads to a quasiparticle picture of an interacting gas, and the virial expansion is linked to the combinants of the distribution. A kinetic model of the liquid-vapor phase transition is presented, in which the particle-number distribution at the critical point converges to the Discrete Stable distribution - the fixed point of a renormalization semi-group transformation. We also show that the scalability of the particle-number distribution is preserved in Tsallis non-extensive thermodynamics, even though infinite divisibility fails. Moreover, deformed discrete distributions, including the negative binomial as a q-deformation of the Poisson, arise naturally in this setting.

Given a simple polygon we aim to find the equation of the straight line which bisects the area of the polygon in a given direction. Additionally, we would like to vary this direction with minimal additional calculation. We provide a solution in the case where the polygon is `bisection-convex', meaning that any straight line bisecting the area of the polygon contains exactly two points on the boundary of the polygon.

For every fixed pair of integers $k\ge 2$ and $q\ge 3$, we prove that every sufficiently large $k$-connected graph $G$ of order $n$ with minimum degree $\delta(G)\ge n/q$ contains a $k$-connected subgraph of every order $\ell\in\{2k,2k+1,\ldots,n\}$. In the case $k=2$, this confirms a conjecture of Liu and Ning~\cite{LiuNing}. The proof combines two constructions. First, we construct a small $k$-connected subgraph $D$ such that every vertex outside $D$ has at least $k$ neighbors in $D$. By successively adding the vertices outside $D$, we obtain $k$-connected subgraphs of every order from $|V(D)|$ to $n$. Second, an averaging argument on common neighborhoods, together with a complete bipartite construction, yields $k$-connected subgraphs of every order from $2k$ to $|V(D)|$. Together, the two constructions cover all orders from $2k$ to $n$. The lower endpoint $2k$ is best possible.

We investigate integrable exclusion Markov processes constructed from set-theoretical solutions of the Yang-Baxter Equation (YBE) that generalise the multi-species Symmetric Simple Exclusion Process (SSEP). We first introduce the process called the $ (p,1) $-SSEP that is analogous to the multi-species SSEP but with an extra particle species qualified as reactive. Reactive species are able to evaporate and condense by pairs or to transform by pairs depending on the interpretation. We provide a full combinatorial study of the sectors in the periodic case. We prove the integrability of the process in the periodic case and in the open case for two types of boundaries that we introduce using Baxterisations of solutions of the reflection equation. Next we move on to the process called $ (p,q) $-SSEP, i.e. the multi-species SSEP with an arbitrary number of reactive particle species. We prove its integrability in the periodic case and, for the open case, we introduce integrable boundaries generalising the ones considered for the $ (p,1) $-SSEP. Finally, we define physical quantities relevant to the models and we compute them in the non-equilibrium stationary state of the open $ (p,q) $-SSEP for one type of integrable boundaries.

The question of the expressive power of a given logical language with Kripke relational semantics has at least two dimensions: (1) what the language can say about frames, and (2) what it can say about models. The Goldblatt-Thomason theorem provides a model-theoretic characterisation of modal axiomatisability for elementary classes of frames in terms of closure under taking generated subframes, disjoint unions, bounded morphic images, and reflection of ultrafilter extensions. Goldblatt also provides a similar characterisation for axiomatisability in intuitionistic logic of classes of models rather than frames. In this article we provide analogous results for bi-intuitionistic logic, a natural expressive extension of intuitionistic logic obtained by adding a binary connective dual to the intuitionistic implication, introduced in the 1970s independently by Dieter Klemke and Cecylia Rauszer. Together with previous results, such as a van Benthem bisimulation characterisation theorem and a Lindstrom theorem, this provides a complete picture of the expressive power of propositional bi-intuitionistic logic.

We study Serrin-type overdetermined problems for a class of possibly degenerate elliptic operators under a vertical boundary condition forcing gradient blow-up. We identify the precise regime in which the problem admits a solution on a ball. In this regime, we prove rigidity: every solution domain is a ball, and the solution is uniquely determined by an explicit radial profile.

The design of state observers for cyber-physical systems under sparse sensor biases, faults, or attacks has drawn substantial attention in recent years. While sparsity-based batch approaches, which collect multiple measurements and run offline, are relatively mature, online secure state estimation, for real-time state/attack recovery, is still an open problem. Although some algorithms have been proposed, convergence guarantees remain limited, even for the case of constant attacks. As a first step toward addressing this gap, we focus on constant attacks. We analyze the observability of this setting and we study several online sparse observers, derived from different methodological frameworks such as online sparse optimization and block Bregman methods. Some of the proposed observers are adaptations of existing algorithms to the secure state-estimation setting, while others constitute novel algorithmic contributions. The goal of this paper is to provide a unified overview of practically implementable, online sparse observers, discuss their convergence properties, and compare their performance through numerical experiments.

This survey invites the readers on a journey spanning more than twenty years of research through the landscape of border basis schemes. During most of this period, I had the pleasure of working with Martin Kreuzer, and more recently with Le Ngoc Long. Along this journey, one encounters border bases, which are characterized by the remarkable property that their associated multiplication matrices commute pairwise. This property, in turn, provides a natural foundation for defining border basis schemes (BBS). These are beautiful schemes, elegantly defined by simple quadratic equations. However, the number of indeterminates in their coordinate rings can be huge. This necessitates a suitable re-embedding into a polynomial ring with fewer indeterminates. This task is accomplished in a more general setting, and the reward is reaped in the BBS scenario, where the notions of cotangent equivalence and exposed indeterminates play a fundamental role, for instance, in showing that planar Box BBS are affine cells. The center stage is taken by positive $P_0$-algebras and the unimodular matrix problem, which allows us to prove that regular algebras of this kind are free. Finally, we turn our attention to special BBS and interesting subschemes of BBS. Are there no more open problems? Fortunately, many remain, and a selection of these challenges marks not a final destination, but a new horizon, suggesting that this journey may continue in the near future. on the border of the soul bases of unseen photographs, schemes of ancient thoughts, slowly return into poems and theorems L. Robbiano, 2026}

The quality of an image observed through a scattering layer, such as a shower curtain, depends strongly on the relative position of the scattering layer between the object and the observer. This well-known phenomenon is commonly referred to as the shower curtain effect. When the scattering layer is placed close to the observer, the image is strongly degraded, whereas if it is located close to the object, the object may still be observed with relatively high resolution. Previous analyses of the shower curtain effect have primarily modeled the scattering layer as a section of a random medium. In this work, we present a new analysis in which the scattering layer is modeled instead as a rough interface, a description that arises naturally in many physical configurations. Within this framework, we derive explicit characterizations of both the image resolution and the signal-to-noise ratio, and determine how these quantities depend on the statistical properties of the rough interface and on its relative location between the object and the observer.

Let $\Phi$ be an irreducible crystallographic root system, and let $Z_\Phi(\mathbf{s})$ denote the untwisted Komori-Matsumoto-Tsumura zeta function with one exponent for each positive coroot. For a nonempty set $S$ of simple nodes, let $H_{S,\ell}$ be the hyperplane on which the exponents of the roots meeting $S$ sum to $|S|-\ell$. We prove that every proper-support hyperplane $H_{S,\ell}$ is a genuine polar divisor at a generic point, whereas exact homogeneity leaves only the unshifted full-support divisor. The residue on $H_{S,\ell}$ is expressed as a finite Taylor-jet sum of reduced projective periods and polynomially weighted complementary root-system zeta functions. On the maximal support wonderful model, boundary terms are indexed by strict decorated flags. We derive recursive flag residues, component-mass gamma factors, and an incidence-complete formula for the Laurent coefficients on any transverse affine slice. In particular, the pole order is determined by the first nonzero aggregate coefficient, not by the largest order of an individual flag. The general formulas recover the classical $A_2$ and $A_3$ singular data, Zhao's Euler-Zagier residues, and the rank-two $C_2$ and $G_2$ residue functions. For $B_3$ and $C_3$ we derive the carrier geometry and the lower-rank factorizations of the positive residues, identify the three-term cancellation at $s=1/8$, and show that negative half-integers are the only possible locations of double poles. The known $B_3$ double coefficient at $-1/2$ is recovered in the flag normalization.

A tree is a partially ordered set that is downwards linear and downwards connected. A tree is called bounded when each of its paths (i.e. maximal linearly ordered subsets) contains a greatest element. In a bounded tree, each path can be defined by a first-order formula using the leaf of the path as parameter. Bounded trees can be used to model computational systems such as Zeno machines whereby the leaf of a path represents the state to which an infinitely long sequence of computations converges, or a state that is assigned to a computational sequence that loops. We identify a sufficient condition under which certain trees that are not bounded, can be elementarily embedded in trees that are bounded. Several tree operations are also given, and Feferman-Vaught style preservation properties for these operations are proved.

A code $C\subseteq F_q^n$ is $(\tau,L)$-list-decodable if every Hamming ball of radius $\tau$ contains at most $L$ codewords of $C$. Here $\tau$ is the list-decoding radius, and $L$ is the list size. Singleton-type bounds constrain the radius and the rate when $L$ is fixed. These bounds are not the only possible constraints on list-decodable codes. In this paper, we derive an upper bound on the list-decoding radius in terms of generalized Hamming weights. As a consequence, for $1\le L\le q-1$, every $(\tau,L)$-list-decodable $q$-ary linear code has minimum distance at least $ \tau+\left\lfloor \frac{\tau}{L}\right\rfloor+1. $ Combining this lower bound with the classical Griesmer bound gives a Griesmer-type lower bound on the block length. For $q=3^a$, we construct an explicit family of $q$-ary linear $[q+3,2,q+1]$ codes. These codes are $(2q/3,2)$-list-decodable and meet the Griesmer-type bound with equality. They do not attain the Singleton-type bound. Thus the Griesmer-type bound can be a strict improvement over the Singleton-type bound.

We consider collisional kinetic equations whose collision operator is not necessarily bilinear and prove quantitative convergence to the Navier-Stokes-Fourier system in weighted Sobolev spaces, together with a description of the initial layers. The aim of this paper is to conciliate the conditional convergence result of Bardos-Golse-Levermore for abstract kinetic equations conserving macroscopic quantities and dissipating entropy with the spectral strategy initiated by Bardos-Ukai for the Boltzmann equation. This work extends the abstract approach of Gervais-Lods which was restricted to bilinear collisions (Boltzmann, Landau or quadratic approximation of other models) to non-bilinear models such as the Boltzmann-Fermi-Dirac equation, the BGK equation and the nonlinear Fokker-Planck equation.

We develop a frugal primal-dual splitting with minimal lifting for solving structured monotone inclusions, involving cocoercive operators, linear compositions and parallel sums. This is established by defining hierarchical nodes and edges between them over a tree-structured graph, with arbitrary assignments of dual variables and cocoercive elements to primal nodes. This arbitrariness allows a great flexibility in terms of level-synchronous distributed computing, such as centralized or decentralized. The particular instances naturally extend the Douglas–Rachford splitting on various graphs, recover the parallel Chambolle–Pock, and solve a class of structured convex minimization problems. For the pure resolvent convex minimization subclass, we establish an O(1/k) ergodic rate for a restricted primal-dual gap over bounded test sets. Furthermore, we introduce a reformulation technique in a product Hilbert space to facilitate the convergence analysis, specifically to derive the o(1/k)-rate of asymptotic regularity

A randomized Singly Diagonally Implicit Runge-Kutta (SDIRK) method, based on the randomized trapezoidal rule as the underlying quadrature scheme, is proposed. Every realization of the scheme is an algebraically stable SDIRK method of at least second order. The main result is the proof that the randomized scheme converges with order 2.5 in the root mean square sense under low regularity assumptions. Numerical experiments illustrate the robustness of the new scheme when applied to nonsmooth problems.

We study the topology and low-degree Hodge theory of moduli spaces of semistable sheaves on bielliptic surfaces. For primitive rank-zero Mukai vectors $\mathbf{v}=(0,c_1(L),\chi)$ satisfying the positivity condition $\operatorname{nt}(L)\geq3$, the distinguished fixed-determinant component $M_{H,S}(\mathbf{v},L)$ admits a support morphism to $|L|$ and is interpreted as a relative compactified Jacobian. Using this fibration, Lefschetz-type properties of positive linear systems, monodromy, and mixed Hodge structures, we construct a surjective homomorphism $ \pi_1(S)\twoheadrightarrow\pi_1\bigl(M_{H,S}(\mathbf{v},L)\bigr) $ and compute the first two Betti numbers of an Albanese fiber $F$, $M_{H,S}(\mathbf{v},L)$, and the distinguished component $M^\circ_{H,S}(\mathbf{v})$. Fourier-Mukai transforms and Bridgeland wall crossing extend these computations to primitive admissible Mukai vectors of positive rank. We further prove that $H^2(F,\mathbb{C})$ is of pure Hodge type $(1,1)$. If $\lambda_S=\ell(\mathbf{v})=1,$ then $F$ is a strict irreducible Calabi-Yau variety up to a finite quasi-étale cover. Under the additional genericity assumption on the pullback polarization, $M^\circ_{H,S}(\mathbf{v})$ is smooth and is noncanonically birational to $\operatorname{Pic}^0(S)\times\operatorname{Hilb}^{\mathbf{v}^2/2}(S)$.

Distributed coordination of multi-agent systems frequently relies on cooperative protocols designed to achieve agreement on a prescribed, non-trivial trajectory. While the robustness of such protocols to various uncertainties is well documented, existing literature universally assumes that the target agreement trajectory itself remains invariant. This assumption may hold in ideal cases, but we prove that network perturbations can vastly modify the asymptotic agreement trajectory. We first investigate the exact trajectories of Linear Time-Invariant (LTI) agents subjected to dynamic coupling uncertainties by establishing a new Laplace-domain criterion that characterizes the specific closed-loop poles governing the perturbed agreement manifold. To formalize our analysis, we introduce the notion of structure-preserving dynamics, perturbations that maintain the null space of the communication graph's Laplacian, and contrast them with transmission only dynamics, affecting only the adjacency matrix. We prove a critical fragility within standard cooperative output regulation schemes: while static consensus is uniquely robust to heterogeneous transmission delays, synchronization to periodic trajectories is destroyed by arbitrarily small transmission delays. Furthermore, we demonstrate that for d-regular topologies, uniform transmission perturbations can easily shift the system to synchronize with an unexpected, entirely new frequency. These findings expose a previously unidentified vulnerability in classical robust synchronization, demonstrating that transmission dynamics necessitate fundamental structural modifications to networked reference generators.

Function-correcting codes have recently emerged as an effective approach to reducing coding redundancy when the objective is to reliably recover only the prescribed function values of the transmitted information, rather than the complete message itself. As a natural generalization of the Hamming metric, the Rosenbloom–Tsfasman metric (RT-metric) has attracted considerable attention due to its relevance to communication over parallel channels. Motivated by these two research directions, we introduce in this paper function-correcting RT codes (FCRTCs), which extend the framework of function-correcting codes from the Hamming metric to the more general RT metric. To investigate the fundamental problem of optimal redundancy, we introduce a new class of matrix codes, called irregular RT-distance codes, and establish a direct correspondence between the redundancy optimization problem for FCRTCs and the construction of such codes. This connection provides a unified framework for deriving redundancy bounds under the RT metric. For arbitrary functions, we establish general upper and lower bounds on the optimal redundancy of FCRTCs. We then specialize our analysis to several important classes of functions, namely RT-weight functions, RT-weight distribution functions, and RT-locally-two-valued binary functions, for which substantially sharper bounds are obtained by exploiting their specific structural properties. Furthermore, we present explicit constructions of FCRTCs for RT-weight distribution functions and prove that these constructions attain the optimal redundancy bounds in several cases. The proposed framework considerably extends the theory of function-correcting codes to the RT metric, provides new theoretical tools for studying reliable communication over parallel channels, and opens new perspectives for redundancy-efficient coding beyond the classical Hamming setting.