The maximal solution of a restricted subadditive inequality in numerical analysis

For a fixed non-negative integerp, letU _2p = {U _2p (n)},n ≥ 0, denote the sequence that is defined by the initial conditions $$U_{2p} (0) = U_{2p} (1) = U_{2p} (2) = = U_{2p} (2p) = 1$$ and the restricted subadditive recursion $$U_{2p} (n + 2p + 1) = \mathop {\min }\limits_{0 \leqslant / \leqslant p} (U_{2p} (n + l) + U_{2p} (n + 2p - l)),n \geqslant 0$$ U _2p is of importance in the theory of sequential search for simple real zeros of real valued continuous 2p-th derivatives In this paper, several closed form expressions forU _2p (n), n > 2p, are determined, thereby providing insight into the structure ofU _2p Two of the properties thus illuminated are (a) the existence of exactlyp + 1 limit points (1 + 1/(p + 1 +i), 0 ≤i ≤p) of the associated sequence {U _2p (n + 1)/U _2p (n)},n ≥ 0, and (b) the relevance toU _2p of the classic number theoretic function ord     

The maximal denumerant of a numerical semigroup

Given a numerical semigroup S=〈a ₀,a ₁,a ₂,…,a _t 〉 and n∈S, we consider the factorization n=c ₀ a ₀+c ₁ a ₁+?+c _t a _t where c _i ≥0. Such a factorization is maximal if ∑c _i is a maximum over all such factorizations of n. We provide an algorithm for computing the maximum number of maximal factorizations possible for an element in S, which is called the maximal denumerant of S. We also consider various cases that have connections to the Cohen-Macualay and Gorenstein properties of associated graded rings for which this algorithm simplifies.     

The numerical analysis on a Volterra equation with asymptotically periodic solution

We consider order one operational quadrature methods on a certain integro-differential equation of Volterra type on $(0,\infty )$, with piecewise linear convolution kernels. The forms of discretization solution are patterned after a continuous one of Hannsgen (1979) [2]. An $l^1$ remainder stability and an error bound are derived.     

The numerical analysis on a Volterra equation with asymptotically periodic solution

We consider order one operational quadrature methods on a certain integro-differential equation of Volterra type on (0,∞), with piecewise linear convolution kernels. The forms of discretization solution are patterned after a continuous one of Hannsgen (1979) [2]. An l¹ remainder stability and an error bound are derived.     

The Fefferman-Stein type inequality for the Kakeya maximal operator

Let , , be the Kakeya maximal operator defined as the supremum of averages over tubes of the eccentricity . We shall prove the so-called Fefferman-Stein type inequality for ,

in the range , , with some constants and independent of and the weight .

     

非紧系统的次可加拓扑压

利用逆紧映射、容许覆盖等概念,将紧系统上的次可加拓扑压推广到非紧系统上,给出了次可加拓扑压的定义,并讨论了非紧系统上次可加拓扑压的性质.     

Experimental analysis of convergence of the numerical solution to a generalized solution in fluid dynamics

Convergence of the approximate solution of fluid dynamics problems obtained using Godunov’s scheme to the discontinuous solution is investigated.     

The restricted EM algorithm under inequality restrictions on the parameters

One of the most powerful algorithms for maximum likelihood estimation for many incomplete-data problems is the EM algorithm. The restricted EM algorithm for maximum likelihood estimation under linear restrictions on the parameters has been handled by Kim and Taylor (J. Amer. Statist. Assoc. 430 (1995) 708-716). This paper proposes an EM algorithm for maximum likelihood estimation under inequality restrictions A₀β?0, where β is the parameter vector in a linear model W=Xβ+ε and ε is an error variable distributed normally with mean zero and a known or unknown variance matrix Σ>0. Some convergence properties of the EM sequence are discussed. Furthermore, we consider the consistency of the restricted EM estimator and a related testing problem.     

Enumeration of maximal subalgebras in free restricted lie algebras

Given a finitely generated restricted Lie algebra L over the finite field \(\mathbb{F}_q \), and n ≥ 0, denote by a _n (L) the number of restricted subalgebras H ? L with \(\dim _{\mathbb{F} _q} \) L/H = n. Denote by ã _n (L) the number of the subalgebras satisfying the maximality condition as well. Considering the free restricted Lie algebra L = F _d of rank d ≥ 2, we find the asymptotics of ã _n (F _d ) and show that it coincides with the asymptotics of a _n (F _d ) which was found previously by the first author. Our approach is based on studying the actions of restricted algebras by derivations on the truncated polynomial rings. We establish that the maximal subalgebras correspond to the so-called primitive actions. This means that “almost all” restricted subalgebras H ? F _d of finite codimension are maximal, which is analogous to the corresponding results for free groups and free associative algebras.     

The Fefferman-Stein type inequality for the Kakeya maximal operator in Wolff's range

Let , , be the Kakeya (Nikodým) maximal operator defined as the supremum of averages over tubes of eccentricity . The (so-called) Fefferman-Stein type inequality:

is shown in the range , where and are some constants depending only on and the dimension and is a weight. The result is a sharp bound up to -factors.

     

Sufficient conditions to compute any solution of a quasivariational inequality via a variational inequality

We define the concept of reproducible map and show that, whenever the constraint map defining the quasivariational inequality (QVI) is reproducible then one can characterize the whole solution set of the QVI as a union of solution sets of some variational inequalities (VI). By exploiting this property, we give sufficient conditions to compute any solution of a generalized Nash equilibrium problem (GNEP) by solving a suitable VI. Finally, we define the class of pseudo-Nash equilibrium problems, which are (not necessarily convex) GNEPs whose solutions can be computed by solving suitable Nash equilibrium problems.     

Severi inequality for varieties of maximal Albanese dimension

In this paper, we prove the general Severi inequality for varieties of maximal Albanese dimension. Suppose that \(X\) is an \(n\) -dimensional projective, normal, minimal and \(\mathbb {Q}\) -Gorenstein variety of general type in characteristic zero. If \(X\) is of maximal Albanese dimension, then \(K^n_X \ge 2 n! \chi (\omega _X)\) .     

On a covering problem related to the centered Hardy-Littlewood maximal inequality

We find the exact value of the best possible constant associated with a covering problem on the real line.     

Estimates for a solution to one differential inequality

In a domain D = Ω × (?T,T) we consider a differential inequality whose left-hand side contains a linear second-order hyperbolic operator with coefficients depending only on x ∈ ? ⁿ, n ≥ 2, and the right-hand side contains the modulus of the gradient of the sought function. We supplement the inequality with the Cauchy data on the lateral part of the boundary of D and consider the problem of estimating a solution to the differential inequality satisfying the Cauchy data. We establish the estimate under some assumptions that involves the upper bound of the sectional curvatures of the Riemannian space associated with the differential operator, the Riemannian diameter of Ω, and the length of the interval (?T,T). The result is generalized to the case of compact domains bounded from above and below by characteristic surfaces.     

On a maximal inequality and its application to SDEs with singular drift

In this paper we present a Doob type maximal inequality for stochastic processes satisfying the conditional increment control condition. If we assume, in addition, that the margins of the process have uniform exponential tail decay, we prove that the supremum of the process decays exponentially in the same manner. Then we apply this result to the construction of the almost everywhere stochastic flow to stochastic differential equations with singular time dependent divergence-free drift.     

Densities of maximal embedding dimension numerical semigroups

We define the density of a numerical semigroup and study the densities of all the maximal embedding dimension numerical semigroups with a fixed Frobenius number, as well as the possible Frobenius number for a fixed density. We also prove that for a given possible density, in the sense of Wilf’s conjecture, one can find a maximal embedding dimension numerical semigroup with that density.     

The numerical solution of linear recurrence relations

By analysing the effect of rounding error on linear recurrence relations having exponential-type complementary solutions, the distribution of two-point boundary conditions most likely to specify a well-conditioned problem is deduced. An intuitive explanation is derived by extending the Bernouilli method of polynomial factorisation to the case of variable coefficients. The replacement of specific boundary conditions by a knowledge of the relative behaviour of the particular and complementary solutions is discussed, and illustrated by examples.