Fixed point equations x = F(x) over omega-continuous semirings are a natural mathematical foundation of interprocedural program analysis. Equations over the semiring of the real numbers can be solved numerically using...
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ISBN:
(纸本)9783540732075
Fixed point equations x = F(x) over omega-continuous semirings are a natural mathematical foundation of interprocedural program analysis. Equations over the semiring of the real numbers can be solved numerically using Newton's method. We generalize the method to any omega)-continuous semiring and show that it converges faster to the least fixed point than the Kleene sequence 0, F (0), F (F (0)),... We prove that the Newton approximants in the semiring of languages coincide with finite-index approximations studied by several authors in the 1960s. Finally, we apply our results to the analysis of stochastic context-free grammars.
Aiming towards a sustainable supply chain, Physical Internet (PI) has been presented as a global logistics network with standardized PI-containers. PI-nodes, and more specifically PI-hubs, are one of the key elements ...
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Aiming towards a sustainable supply chain, Physical Internet (PI) has been presented as a global logistics network with standardized PI-containers. PI-nodes, and more specifically PI-hubs, are one of the key elements of the Physical Internet concept. This paper focuses on optimising operations in the Road-Road PI-hub, which was not addressed in the Physical Internet literature. Road-Road PI-hubs are designed to transfer PI-containers between suppliers' and customers' trucks. The objective is to minimize both the inbound/outbound trucks delays and the energy consumption during the transferring of PI-containers using PI-conveyors. The problem is formulated as a multi-objective mixed integer model (MO-MIP) to find the optimal Pareto front. The mathematical model is tested on an illustrative instance to show the tradeoff between trucks' delays and PI-containers routing energy consumption. The primary goal of this paper is to provide a prospect to start optimizing PI-hubs by suggesting a multi-objective mathematical model as a beginning for future researches on the Road-Road PI-hubs. Copyright (C) 2021 The Authors.
Purpose In emergency services, maximizing population coverage with the lowest cost at the peak of the demand is important. In addition, due to the nature of services in emergency centers, including hospitals, the numb...
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Purpose In emergency services, maximizing population coverage with the lowest cost at the peak of the demand is important. In addition, due to the nature of services in emergency centers, including hospitals, the number of servers and beds is actually considered as the capacity of the system. Hence, the purpose of this paper is to propose a multi-objective maximal covering facility location model for emergency service centers within an M ((t))/M/m/m queuing system considering different levels of service and periodic demand rate. Design/methodology/approach The process of serving patients is modeled according to queuing theory and mathematical programming. To cope with multi-objectiveness of the proposed model, an augmented epsilon-constraint method has been used within GAMS software. Since the computational time ascends exponentially as the problem size increases, the GAMS software is not able to solve large-scale problems. Thus, a NSGA-II algorithm has been proposed to solve this category of problems and results have been compared with GAMS through random generated sample problems. In addition, the applicability of the proposed model in real situations has been examined within a case study in Iran. Findings Results obtained from the random generated sample problems illustrated while both the GAMS software and NSGA-II almost share the same quality of solution, the CPU execution time of the proposed NSGA-II algorithm is lower than GAMS significantly. Furthermore, the results of solving the model for case study approve that the model is able to determine the location of the required facilities and allocate demand areas to them appropriately. Originality/value In the most of previous works on emergency services, maximal coverage with the minimum cost were the main objectives. Hereby, it seems that minimizing the number of waiting patients for receiving services have been neglected. To the best of the authors' knowledge, it is the first time that a maximal covering prob
The purpose of this paper is to establish sufficient conditions for the existence of solutions to mathematical programs where the variables of the solution satisfy given proportions. These conditions rely on convergen...
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We settle the fundamental problem of estimating the mean of a real-valued distribution in the high probability regime, under the minimal (and essentially necessary) assumption that the distribution has finite but unkn...
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ISBN:
(纸本)9781665420556
We settle the fundamental problem of estimating the mean of a real-valued distribution in the high probability regime, under the minimal (and essentially necessary) assumption that the distribution has finite but unknown variance: we propose an estimator with convergence tight up to a 1 + o(1) factor. Crucially, in contrast to prior works, our estimator does not require prior knowledge of the variance, and works across the entire gamut of distributions with finite variance, including those without any higher moments. Parameterized by the sample size n, the failure probability delta, and the variance sigma(2), our estimator has additive accuracy within sigma. (1 + o(1))root 2 log 1/delta/n, which is optimal up to the 1 + o(1) term. This asymptotically matches the convergence of the sample mean for the Gaussian distribution with the same variance. Our estimator construction and analysis gives a framework generalizable to other problems, tightly analyzing a sum of dependent random variables by viewing the sum implicitly as a 2-parameter psi-estimator, and constructing bounds using mathematical programming and duality techniques.
Network slicing is an important characteristic of 5G/6G networks that increases flexibility and enables different applications over a single infrastructure. The physical resources are partitioned to create virtualized...
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ISBN:
(纸本)9798350399806
Network slicing is an important characteristic of 5G/6G networks that increases flexibility and enables different applications over a single infrastructure. The physical resources are partitioned to create virtualized networks, each dedicated to services with specific requirements. Several entities participate in network slicing, including Mobile Network Operators (MNOs), Mobile Virtual Network Operators (MVNOs), and users. An MNO owns the physical network infrastructure and the resources. MVNOs lease resources from the MNO and operate as service providers towards their subscribers. The goal of this work is to optimize the end-to-end network slicing process to provide services to users with a fair sharing of resources. We model this problem as a hierarchical combinatorial auction with a modified Vickrey-Clarke-Groves pricing mechanism. In the upper-level auction, an MNO is the seller supplying Network Slice to several MVNOs, who act as the bidders. In the lower-level auction, each MVNO holds an auction as a seller delivering services to their subscribed end-users, who play the role of bidders. We formulate and solve theWinner Determination Problem using mathematical programming and heuristic algorithms. The simulations show that the model can achieve fair sharing of resources, and it enables improving the MNO and MVNO revenue.
In this paper we introduce the concepts of fuzzy space, the distances between points and sets of this space. In addition, a concept of a polyhedral fuzzy set, a convex hull, and a fuzzy direction are proposed. It is p...
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ISBN:
(纸本)9781509062607
In this paper we introduce the concepts of fuzzy space, the distances between points and sets of this space. In addition, a concept of a polyhedral fuzzy set, a convex hull, and a fuzzy direction are proposed. It is proved that a polyhedral fuzzy set is a convex hull of a finite number of fuzzy points and directions. In accordance with the main result of this paper any convex closed fuzzy set with a continuous membership function can be approximated with any degree of accuracy by a fuzzy polytop.
This paper provides a nuclear norm minimization approach to an identification of linear systems with finite word-length data. Measurement data sampled from low resolution sensors are sequence of a few bit data and hav...
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ISBN:
(纸本)9781424452262
This paper provides a nuclear norm minimization approach to an identification of linear systems with finite word-length data. Measurement data sampled from low resolution sensors are sequence of a few bit data and have large quantization errors, which deteriorate the identification accuracy. In this paper, the identification problem is formulated as a rank minimization problem, and the nuclear norm heuristic is introduced to estimate the model order and precise values of finite word-length data. An iterative algorithm is proposed based on the weighted nuclear norm minimization and its semidefinite programming formulation. Numerical examples demonstrate that we can estimate both the model order and parameters and show the effectiveness of the proposed method.
IT projects are characterized by high complexity, implementation of the latest technological solutions and specialized competence of contractors and high costs. The key element in IT project management is to have empl...
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ISBN:
(纸本)9783030420581;9783030420574
IT projects are characterized by high complexity, implementation of the latest technological solutions and specialized competence of contractors and high costs. The key element in IT project management is to have employees with appropriate substantive competencies (programmers, designers, analysts, etc.). Before starting an IT project, the IT project manager must answer the following questions: Do I have the right set of team competences to start the project? If the team lacks competence, then in what area and to what extent? The article proposes a model of employee competence configuration and a procedure for their verification in the context of IT project management. Also presented is the method of model implementation and numerous computational examples verifying its usefulness and effectiveness of implementation.
It is shown that there are categorical differences between sentences and statements, which have the consequence in particular that there are no paradoxical cases of self-reference with the latter as there are with the...
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It is shown that there are categorical differences between sentences and statements, which have the consequence in particular that there are no paradoxical cases of self-reference with the latter as there are with the former. The point corrects an extensive train of thought that Graham Priest has pursued over recent years, but also a much wider tradition in logic and the foundations of mathematics that has been dominant for over a century. That tradition might be broadly characterized as Formalist, or Nominalist, and the improved understanding of statements leads us instead into a more Realist approach and thereby contentful logic and mathematics.
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