This paper introduces an open conjecture in time-frequency analysis on the linear independence of a finite set of time-frequency shifts of a given L² function. Firstly, background and motivation for the conjecture are provided. Secondly, the main progress of this linear independence in the past twenty five years is reviewed. Finally, the partial results of the high dimensional case and other cases for the conjecture are briefly presented.

Let (M,g) be a Kähler surface and \mathrm{\Sigma } be a \beta-symplectic critical surface in M. If L_q\left(\mathrm{\Sigma }\right) is bounded for some q>3, then we give a uniform upper bound for the Kähler angle on \mathrm{\Sigma }. This bound only depends on M,q,\beta and the L_q functional of \mathrm{\Sigma }. For q>4, this estimate is known and we extend the scope of q.

In this paper, we study some kinds of generalized valuations on MTL-algebras, discuss the relationship between the cokernel of generalized valuations and types of filters on MTL-algebras. Then, we give some equivalent characterizations of positive implicative generalized valuations on MTL-algebras. Finally, we characterize the structure theory of quotient MTL algebras based on the congruence relation, which is constructed by generalized valuations. The results of this paper not only generalize related theories of generalized valuations, but also enrich the algebraic conclusion of probability measure, on algebras of triangular norm based fuzzy logic.

Let p>0 and \nu be a normal function on [0,1). In this paper, several equivalent characterizations are given for which composition operators are bounded or compact on the normal weight Dirichlet type space {\mathcal{D}}_{\nu }^p \left(D\right) in the unit disc.

In 2020, Niu et al. [Cryptogr. Commun., 2020, 12(2): 165−185] studied the fixed points of involutions over the finite field with q-elements. This paper further discusses the relationship between the fixed points set and the non-fixed points set of two involutions f_1\left(x \right) and f_2\left(x \right) over the finite field {\mathbb{F}}_q, and then obtains a necessary and sufficient condition for that the composite function f_1\circ f_2\left(x \right) is also an involution over {\mathbb{F}}_q. In particular, a special class of involutions over some finite fields is determined completely.

Let G be a finite group, p be a prime divisor of |G|, and P be a Sylow p-subgroup of G. We prove that P is normal in a solvable group G if |G : ker φ|p' = φ(1)p' for every nonlinear irreducible monomial p-Brauer character φ of G, where ker φ is the kernel of φ and φ(1)p' is the p'-part of φ(1).

We establish some results on the complete moment convergence for weighted sums of widely orthant-dependent (WOD) random variables, which improve and extend the corresponding results of Y. F. Wu, M. G. Zhai, and J. Y. Peng [J. Math. Inequal., 2019, 13(1): 251–260]. As an application of the main results, we investigate the complete consistency for the estimator in a nonparametric regression model based on WOD errors and provide some simulations to verify our theoretical results.

The data clustering problem consists in dividing a data set into prescribed groups of homogeneous data. This is an NP-hard problem that can be relaxed in the spectral graph theory, where the optimal cuts of a graph are related to the eigenvalues of graph 1-Laplacian. In this paper, we first give new notations to describe the paths, among critical eigenvectors of the graph 1-Laplacian, realizing sets with prescribed genus. We introduce the pseudo-orthogonality to characterize m₃(G), a special eigenvalue for the graph 1-Laplacian. Furthermore, we use it to give an upper bound for the third graph Cheeger constant h₃(G), that is, h₃(G) 6 m₃(G). This is a first step for proving that the k-th Cheeger constant is the minimum of the 1-Laplacian Raylegh quotient among vectors that are pseudo-orthogonal to the vectors realizing the previous k - 1 Cheeger constants. Eventually, we apply these results to give a method and a numerical algorithm to compute m₃(G), based on a generalized inverse power method.

We obtain the characterizations of commutators of several versions of maximal functions on spaces of homogeneous type. In addition, with the aid of interpolation theory, we provide weighted version of the commutator theorems by establishing new characterizations of the weighted BMO space. Finally, a concrete example shows that the local version of commutators also has an independent interest.

Let G be a simple connected graph with n vertices. The transmission T_v of a vertex v is defined to be the sum of the distances from v to all other vertices in G, that is, T_v = Σ_u∈V d_uv, where d_uv denotes the distance between u and v. Let T₁, ..., T_n be the transmission sequence of G. Let D = (d_ij)_n×n be the distance matrix of G, and \mathfrak{T} be the transmission diagonal matrix diag(T₁, ..., T_n). The matrix $$\mathcal{Q}(G)=\mathcal{T}+\mathcal{D}$$ is called the distance signless Laplacian of G. In this paper, we provide the distance signless Laplacian spectrum of complete k-partite graph, and give some sharp lower and upper bounds on the distance signless Laplacian spectral radius q(G).

We study the Markov decision processes under the average-valueat-risk criterion. The state space and the action space are Borel spaces, the costs are admitted to be unbounded from above, and the discount factors are state-action dependent. Under suitable conditions, we establish the existence of optimal deterministic stationary policies. Furthermore, we apply our main results to a cash-balance model.

The main purpose of this paper is to solve the viscous Cahn-Hilliard equation via a fast algorithm based on the two time-mesh (TT-M) finite element (FE) method to ease the problem caused by strong nonlinearities. The TT-M FE algorithm includes the following main computing steps. First, a nonlinear FE method is applied on a coarse time-mesh τ_c. Here, the FE method is used for spatial discretization and the implicit second-order θ scheme (containing both implicit Crank-Nicolson and second-order backward difference) is used for temporal discretization. Second, based on the chosen initial iterative value, a linearized FE system on time fine mesh is solved, where some useful coarse numerical solutions are found by Lagrange’s interpolation formula. The analysis for both stability and a priori error estimates is made in detail. Numerical examples are given to demonstrate the validity of the proposed algorithm. Our algorithm is compared with the traditional Galerkin FE method and it is evident that our fast algorithm can save computational time.

We introduce the concept of weak silting modules, which is a generalization of both silting modules and Tor-tilting modules. It is shown that W is a weak silting module if and only if its character module W⁺ is cosilting. Some properties of weak silting modules are given.

We investigate a particle system with mean field interaction living in a random environment characterized by a regime-switching process. The switching process is allowed to be dependent on the particle system. The well-posedness and various properties of the limit conditional McKean-Vlasov SDEs are studied, and the conditional propagation of chaos is established with explicit estimate of the convergence rate.