Lazy Reachability Analysis in Distributed Systems

We address the problem of reachability in distributed systems, modelled as networks of finite automata and propose and prove a new algorithm to solve it efficiently in many cases. This algorithm allows to decompose the reachability objective among the components, and proceeds by constructing partial products by lazily adding new components when required. It thus constructs more and more precise over-approximations of the complete product. This permits early termination in many cases, in particular when the objective is not reachable, which often is an unfavorable case in reachability analysis. We have implemented this algorithm in an early prototype and provide some very encouraging experimental results

A Practical Introduction to MapServer

Platinum Sponsors * KU Department of Geography * KU Institute for Policy & Social Research Gold Sponsors * State of Kansas Data Access and Support Center (DASC) * KU Libraries GIS and Scholar Services * KU Transportation Research Institute * Wilson & Company (formerly Western Air Maps) Silver Sponsors * Bartlett & West * KU Biodiversity Institute * KansasView Consortium Bronze Sponsors * Coca-Cola * Kansas Biological Survey/Kansas Applied Remote Sensing (KARS) * KU Center for Remote Sensing of Ice Sheets (CReSIS) * KU Department of Civil, Environmental and Architectural Engineering * Black & Veatch * Spatial Data Research * AECOM * MJ Harde

Performance evaluation of an emergency call center: tropical polynomial systems applied to timed Petri nets

We analyze a timed Petri net model of an emergency call center which processes calls with different levels of priority. The counter variables of the Petri net represent the cumulated number of events as a function of time. We show that these variables are determined by a piecewise linear dynamical system. We also prove that computing the stationary regimes of the associated fluid dynamics reduces to solving a polynomial system over a tropical (min-plus) semifield of germs. This leads to explicit formul{\ae} expressing the throughput of the fluid system as a piecewise linear function of the resources, revealing the existence of different congestion phases. Numerical experiments show that the analysis of the fluid dynamics yields a good approximation of the real throughput.Comment: 21 pages, 4 figures. A shorter version can be found in the proceedings of the conference FORMATS 201

Integrated Model-checking for the Design of Safe and Efficient Distributed Software Commissioning

International audienc

Parameter Synthesis for Parametric Interval Markov Chains

AELOS_HCERES2020, STR_HCERES2020Interval Markov Chains (IMCs) are the base of a classic probabilistic specification theory introduced by Larsen and Jonsson in 1991. They are also a popular abstraction for probabilistic systems. In this paper we study parameter synthesis for a parametric extension of Interval Markov Chains in which the endpoints of intervals may be replaced with parameters. In particular, we propose constructions for the synthesis of all parameter values ensuring several properties such as consistency and consistent reachability in both the existential and universal settings with respect to implementations. We also discuss how our constructions can be modified in order to synthesise all parameter values ensuring other typical properties

Formal Verification of Real-time Systems with Preemptive Scheduling

International audienceIn this paper, we propose a method for the verification of timed properties for real-time systems featuring a preemptive scheduling policy: the system, modeled as a scheduling time Petri net, is first translated into a linear hybrid automaton to which it is time-bisimilar. Timed properties can then be verified using HyTech. The efficiency of this approach leans on two major points: first, the translation features a minimization of the number of variables (clocks) of the resulting automaton, which is a critical parameter for the efficiency of the ensuing verification. Second, the translation is performed by an over-approximating algorithm, which is based on Difference Bound Matrix and therefore efficient, that nonetheless produces a time-bisimilar automaton despite the over-approximation. The proposed modeling and verification method are generic enough to account for many scheduling policies. In this paper, we specifically show how to deal with Fixed Priority and Earliest Deadline First policies, with the possibility of using Round-Robin for tasks with the same priority. We have implemented the method and give some experimental results illustrating its efficiency

A Consumer Test of Citrus Drinks made from Comminuted Whole Citrus Fruit

Consumer, Citrus, Whole Citrus Fruit, Citrus Fruit, Consumer Test, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

Cooperation In Resource Management Planning: A Model Process for Promoting Partnerships Between Resource Managers and Private Service Providers

This study presents a modified transactive planning process intended to improve communication and cooperation between public sector resource managers and private sector businesses that serve visitors to an outdoor recreation resource. The elements of the transactive planning process are illustrated and applied in a case study approach with the U.S. Forest Service and commercial outfitters adjacent to a forest recreation area. Outcomes of the planning process indicate that public managers and private businesses share many of the same management goals and concerns. They also agree they can and should address these concerns cooperatively. Results of the study indicate that this transactive process: (1) can promote cooperation and improved communication between public managers and private sector service businesses, and (2) can be effectively integrated into the implementation phase of the traditional allocative planning model on which most public resource agencies rely. Strengths and weaknesses of the transactive planning process are discussed