Generalized Post Embedding Problems

The Regular Post Embedding Problem extended with partial (co)directness is shown decidable. This extends to universal and/or counting versions. It is also shown that combining directness and codirectness in Post Embedding problems leads to undecidability.     

Graph Classification by Means of Lipschitz Embedding

In pattern recognition and related fields, graph-based representations offer a versatile alternative to the widely used feature vectors. Therefore, an emerging trend of representing objects by graphs can be observed. This trend is intensified by the development of novel approaches in graph-based machine learning, such as graph kernels or graph-embedding techniques. These procedures overcome a major drawback of graphs, which consists of a serious lack of algorithms for classification. This paper is inspired by the idea of representing graphs through dissimilarities and extends our previous work to the more general setting of Lipschitz embeddings. In an experimental evaluation, we empirically confirm that classifiers that rely on the original graph distances can be outperformed by a classification system using the Lipschitz embedded graphs.     

Explicit Galois Realization of Transitive Groups of Degree up to 15

We describe methods for the construction of polynomials with certain types of Galois groups. As an application we deduce that all transitive groups G up to degree 15 occur as Galois groups of regular extensions ofQ (t), and in each case compute a polynomial f  Q [ x ] with Gal(f)  = G.     

Galois Action on Solutions of a Differential Equation

Consider a second-order differential equation of the form y″ + ay ′ + by = 0 with a, b ϵ Q(x). Kovacic's algorithm tries to compute a solution of the associated Riccati equation that is algebraic and of minimal degree over Q̄ (x). The coefficients of the monic irreducible polynomial of this solution are in C(x), where C is a finite algebraic extension of Q. In this paper we give a bound for the degree of the extension C ⊃ Q. Similar results are obtained for third-order differential equations.     

基于语义嵌入模型与交易信息的智能合约自动分类系统

作为区块链技术的一个突破性扩展,智能合约允许用户在区块链上实现个性化的代码逻辑从而使得区块链技术更加的简单易用.在智能合约代码信息迅速增长的背景下,如何管理和组织海量智能合约代码变得更具挑战性.基于人工智能技术的代码分类系统能根据代码的文本信息自动分门别类,从而更好地帮助人们管理和组织代码的信息.本文以Ethereum平台上的智能合约为例,鉴于词嵌入模型可以捕获代码的语义信息,提出一种基于词嵌入模型的智能合约分类系统.另外,每一个智能合约都关联着一系列交易,我们又通过智能合约的交易信息来更深入地了解智能合约的逻辑行为.据我们所知,本文是对智能合约代码自动分类问题的首次研究尝试.测试结果显示该系统具有较为令人满意的分类性能.     

交换超立方网络的嵌入问题研究

交换超立方网络作为超立方网络的一个变种,具有良好的递归性和理想的网络参数。根据交换超立方网络的相关性质研究了E-2DMesh网络和超立方网络的嵌入问题,并得出如下结论:(1)当max(s,t)<7时,不存在dilation=1的EM(2m,2n)到EH(s,t)的嵌入映射(m+n≤s+t+1)。(2)EM(2s,2t)可以expansion=2,dilation=4,load=1嵌入EH(s,t)。(3)当min(s,t)>1时,不存在dilation=1的Qn到EH(s,t)的嵌入映射(n=s+t)。(4)Qn可以ex-pansion=2,dilation=3,congestion=1,load=1嵌入EH(s,t)(n=s+t)。上述结论进一步说明了交换超立方网络具有良好的扩容性。     

Search for Polynomial Solutions of Linear Functional Systems by Means of Induced Recurrences

The problem of searching for polynomial solutions of linear functional (differential, difference, and q-difference) equations is considered. The problem is solved by means of the construction of an induced recurrent system in the coefficients of the expansion of the desired solution in a certain basis. In the paper, practical aspects of the construction of such induced recurrences are discussed, and a new algorithm for the construction of polynomial solutions based on them is suggested.     

Partially-Linear Transportation Problems, Obtained by Means of Absolute Value Functions

Nonlinear transportation problems may be successfully used to model problems in economics, due to the nonlinear relationship between quantities and the real cost for their transportation. In this paper we consider transportation problems with two-piece linear functions on arcs (which may be nonconvex), where the nonlinearity is represented by absolute value functions. A necessary and sufficient condition for local optimality is given and an algorithm for solving these problems is suggested.     

Evaluation of Generalized Force Derivatives by Means of a Recursive Newton–Euler Approach

An accurate estimation of the dynamics efforts acting on a robot manipulator represents an important issue for both the analysis of its behavior and the synthesis of appropriate controllers. This paper proposes an iterative algorithm, which is based on the Newton–Euler approach, for the efficient evaluation of the manipulators' high-order kinematics and dynamics. In particular, the algorithm computes velocities, accelerations, and jerks of each link, while new dynamic equations are devised in order to evaluate the first derivative of generalized forces. Due to its moderate computational burden, the algorithm is suited to be used in online applications.      

A Study of Reinforcement Learning in the Continuous Case by the Means of Viscosity Solutions

This paper proposes a study of Reinforcement Learning (RL) for continuous state-space and time control problems, based on the theoretical framework of viscosity solutions (VSs). We use the method of dynamic programming (DP) which introduces the value function (VF), expectation of the best future cumulative reinforcement. In the continuous case, the value function satisfies a non-linear first (or second) order (depending on the deterministic or stochastic aspect of the process) differential equation called the Hamilton-Jacobi-Bellman (HJB) equation. It is well known that there exists an infinity of generalized solutions (differentiable almost everywhere) to this equation, other than the VF. We show that gradient-descent methods may converge to one of these generalized solutions, thus failing to find the optimal control.In order to solve the HJB equation, we use the powerful framework of viscosity solutions and state that there exists a unique viscosity solution to the HJB equation, which is the value function. Then, we use another main result of VSs (their stability when passing to the limit) to prove the convergence of numerical approximations schemes based on finite difference (FD) and finite element (FE) methods. These methods discretize, at some resolution, the HJB equation into a DP equation of a Markov Decision Process (MDP), which can be solved by DP methods (thanks to a strong contraction property) if all the initial data (the state dynamics and the reinforcement function) were perfectly known. However, in the RL approach, as we consider a system in interaction with some a priori (at least partially) unknown environment, which learns from experience, the initial data are not perfectly known but have to be approximated during learning. The main contribution of this work is to derive a general convergence theorem for RL algorithms when one uses only approximations (in a sense of satisfying some weak contraction property) of the initial data. This result can be used for model-based or model-free RL algorithms, with off-line or on-line updating methods, for deterministic or stochastic state dynamics (though this latter case is not described here), and based on FE or FD discretization methods. It is illustrated with several RL algorithms and one numerical simulation for the Car on the Hill problem.     

Problems of Plaintext Embedding on Elliptic Curve and Their Apphcatlons

Problems of plaintext embedding on elliptic curve are considered in this paper. We present the embedding algorithm on binary field and make a comparison with it on prime field on performance. In the end we provide some applications on storage and transmission of points in elliptic CHIVe.     

计算机常见问题解决办法

通过对中国农业博物馆(全国农业展览馆)的近年来计算机维修和维护情况的调查和统计,并结合几年实际维护的经验,发现计算机使用过程中的硬件问题通常都需要专业人员解决,而软件问题通常都是病毒或木马程序引起的,用最新的杀毒软件基本都能解决.本文总结出的计算机常见问题实用解决办法.     

计算机常见问题解决办法

通过对中国农业博物馆（全国农业展览馆）的近年来计算机维修和维护情况的调查和统计,并结合几年实际维护的经验,发现计算机使用过程中的硬件问题通常都需要专业人员解决,而软件问题通常都是病毒或木马程序引起的,用最新的杀毒软件基本都能解决。本文总结出的计算机常见问题实用解决办法。     

SQL Server数据库系统的性能优化策略研究

随着数据库技术的发展、数据量的增大,SQL Server数据库性能优化的问题也越发被人们所重视。本文对SQL Server数据库系统从设计、查询、存储过程三个方面在性能的优化中常见的问题提出一些看法和建议。     

基于稀疏解组合优化的广义重心坐标

根据广义重心坐标线性运算的性质与特点,运用广义重心坐标的稀疏解权函数的 调和平均组合方法,对空间凸多面体顶点设计了一种求解广义重心坐标的算法,且权函数是带 有保形参数的一元函数,因而具有保形优化的特点。构造了 2 种不同类型的带形参权函数,运 用不同权函数及其参数的广义重心坐标将平面图形映射到空间曲面的实例进行了分析,并应用 重心坐标常用的等值线工具对保形性进行了比较。     

电能计量的常见问题与对策

结合我国电力供应的现状,分析电能计量的常见问题,并提出有针对性的解决策略.     

Windows XP系统故障及解决方案

Windows XP系统的界面友好、性能也相对稳定,如今已经成为个人用户装机的首选操作系统。但是在安装、使用WINXP的过程中,难免会遇到许多问题,如何在不重装系统的前提下快速地解决这些问题,让电脑恢复正常呢?本文从多年的实践经验出发,让更多的朋友掌握正确的方法和技巧,轻松排除故障。     

计算机信息处理存在的问题及解决对策

随着经济的飞速发展和技术的不断更新换代,计算机信息处理逐渐发展。由于其具有高效率的数据处理特点,因此被广泛运用。计算机信息处理技术从实质上提高了信息处理的效率,但计算机信息处理过程中存在一系列问题。基于此,以计算机信息处理存在的问题为研究对象展开分析,并提出相对应的解决对策,以期为相关人士提供一定参考。