arXiv Math @arxiv_math@qoto.org

This paper explores the evolution and monotonicity of geometric constants within the framework of extended Ricci flows, incorporating variable coupling parameters. Building on Hamiltons foundational Ricci flow and subsequent extensions by List (2008), we introduce modifications to the extended Ricci flow by varying parameters that affect the interaction between the metric and scalar fields. Specifically, we modify the coefficients in the evolution equations governing geometric constants, thereby introducing new degrees of freedom in the analysis. The primary contributions include deriving evolution formulas for the modified geometric constant lambda under the extended and normalized extended Ricci flows, and proving conditions under which monotonicity is maintained.

A parameter of a mathematical model is structurally identifiable if it can be determined from noiseless experimental data. Here, we examine the identifiability properties of two important classes of linear compartmental models: directed-cycle models and catenary models (models for which the underlying graph is a directed cycle or a bidirected path, respectively). Our main result is a complete characterization of the directed-cycle models for which every parameter is (generically, locally) identifiable. Additionally, for catenary models, we give a formula for their input-output equations. Such equations are used to analyze identifiability, so we expect our formula to support future analyses into the identifiability of catenary models. Our proofs rely on prior results on input-output equations, and we also use techniques from linear algebra and graph theory.

In the work "Generalized approximation spaces generation from $\mathbb{I}_{j}$-neighborhoods and ideals with application to Chikungunya disease, published in \emph{AIMS Mathematics}, \textbf{9}(4) (2024), 10050$-$10077," Al-Shami and Hosny introduced a novel approach for generating generalized neighborhoods through $\mathbb{I}_{j}$-neighborhoods with ideals, subsequently deriving new methods for generalized approximations based on these neighborhoods. However, several errors have been identified in their results, concepts, and methods, along with significant inaccuracies in the provided examples and comparison tables. This paper aims to address and correct these errors, providing counterexamples to illustrate the inaccuracies in the proposed results. Furthermore, we correct several flawed proofs and present the revised formulations of these results and concepts. Additionally, we offer properties and clarifications to enhance the understanding of these concepts.

In this paper, we propose $λ_{g}$ conjecture for Hodge integrals with target varieties. Then we establish relations between Virasoro conjecture and $λ_{g}$ conjecture, in particular, we prove $λ_{g}$ conjecture in all genus for smooth projective varieties with semisimple quantum cohomology or smooth algebraic curves. Meanwhile, we also prove $λ_{g}$ conjecture in genus zero for any smooth projective varieties. In the end, together with DR formula for $λ_g$ class, we obtain a new type of universal constraints for descendant Gromov-Witten invariants. As an application, we prove $λ_{g}$ conjecture in genus one for any smooth projective varieties.

Due to the processes that occur during the functioning of modern electromechanical systems, these systems can be considered complex nonlinear dynamic systems from the point of view of the theory of dynamic systems. The movement of such systems is completely determined by external influences acting on the EMS, their parameters, and initial operating conditions. The above-mentioned factors complicate the study of electromechanical systems and, in the general case, make it impossible to use classical methods of analyzing the dynamics of the EMS since the latter neglect the features of nonlinear systems and describe their dynamics using ordinary linear differential equations with constant coefficients. At the same time, many methods and approaches have been developed in control theory for analyzing stability and synthesizing motion trajectories based on linear differential equations. Therefore, an important task arises to create mathematical models of nonlinear EMS that consider the peculiarities of their motion but have a form similar to linear models.

This article is devoted to the classification of anti-dendriform algebras that are associated with associativity. They are characterized as algebras with two operations whose sum is associative. In the paper all four-dimensional complex anti-dendriform algebras associated to four-dimensional associative algebras with one-dimensional center are classified

In this work, we investigate the long-time behavior of solutions to the non-cutoff Boltzmann equation on compact Riemannian manifolds with bounded Ricci curvature. The paper introduces new results on the exponential decay of hydrodynamic quantities, such as density, momentum, and energy fields, influenced by both the curvature of the manifold and singularities in the collision kernel. We demonstrate that for initial data in $H^s_x \times L^p_v$, the solutions exhibit sharp exponential decay rates in Sobolev norms, with the decay rate determined by the manifold's geometry and the regularity of the kernel. Specifically, we prove that the density $ρ(t, x)$, momentum $\mathbf{m}(t, x)$, and energy field $E(t, x)$ all decay exponentially in time, with decay rates that depend on the manifold's curvature and the nature of the collision kernel's singularity. Additionally, we address the case of angular singularities in the collision kernel, providing conditions under which the exponential decay persists. The analysis combines energy methods, Fourier analysis, and coercivity estimates for the collision operator, extended to curved geometries. These results extend the understanding of dissipation mechanisms in kinetic theory, especially in curved settings, and offer valuable insights into the behavior of rarefied gases and plasma flows in non-Euclidean environments. The findings have applications in plasma physics, astrophysics, and the study of rarefied gases, opening new directions for future research in kinetic theory and geometric analysis.

The purpose of this paper is to explore properties of the whisker topology, which is a topology endowed on the fundamental group and whose utility is to detect locally complicated phenomena in pathological topological spaces. We show that the whisker topology preserves products, resolve an open question regarding the existence of a space which makes $π_1^{wh}(X,x_0)$ a non-discrete, non-abelian, and Hausdorff topological group, and show the whisker topology is not separable on the earring group $π_1(\Er^1,x_0)$.

The longstanding Godbersen's conjecture states that for any convex body $K \subset \mathbb R^n$ of volume $1$ and any $j \in \{0, \ldots, n\}$, the mixed volume $V_j = V(K[j], -K[n - j])$ is bounded by $\binom{n}{j}$, with equality if and only if $K$ is a simplex. We demonstrate that several consequences of this conjecture are true: certain families of linear combinations of the $V_j$, arising from different geometric constructions, are bounded above by their values when one substitutes $\binom{n}{j}$ for $V_j$, with equality if and only if $K$ is a simplex. One of our results implies that for any $K$ of volume $1$ we have $\frac{1}{n + 1} \sum_{j = 0}^n \binom{n}{j}^{-1} V_j \le 1$, showing that Godbersen's conjecture holds ``on average'' for any body. Another result generalizes the well-known Rogers-Shephard inequality for the difference body.

This research paper talks about using complex mathematical tools to study and figure out the behavior of biological populations in porous media. Porous media offer a unique environment where various factors, including fluid flow and nutrient diffusion, significantly influence population dynamics. The theory of Lie symmetries is used to find inherent symmetries in the governing equation of the population model, helping to find conservation laws and invariant solutions. The derivation and analysis of the optimal system provide insights into the most influential parameters affecting population growth and distribution. Furthermore, the study explores the construction of invariant solutions, which aid in characterizing long-term population behavior. The article concludes with the non-linear self-adjointness property and conservation laws for the model.