328 research outputs found
Real-time MTL with durations as SMT with applications to schedulability analysis
This paper introduces a synthesis procedure for the satisfiability problem of RMTL-D formulas as SAT solving modulo theories. RMTL-D is a real-time version of metric temporal logic (MTL) extended by a duration quantifier allowing to measure time durations. For any given formula, a SAT instance modulo the theory of arrays, uninterpreted functions with equality and non-linear real-arithmetic is synthesized and may then be further investigated using appropriate SMT solvers. We show the benefits of using RMTL-D with the given SMT encoding on a diversified set of examples that include in particular its application in the area of schedulability analysis. Therefore, we introduce a simple language for formalizing schedulability problems and show how to formulate timing constraints as RMTL-D formulas. Our practical evaluation based on our synthesis and Z3 as back-end SMT solver also shows the feasibility of the overall approach.This work was partially supported by BMVI project IHATEC / SecurePort; by National Funds through FCT/M- CTES (Portuguese Foundation for Science and Technology), within the CISTER Research Unit (UID/CEC/04234) and the INESC TEC (UIDB/50014/2020); also by the Norte Portugal Regional Operational Programme (NORTE 2020) under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (ERDF) and also by national funds through the FCT, within project NORTE-01-0145- FEDER-028550 (REASSURE)
An executable Theory of Multi-Agent Systems Refinement
Complex applications such as incident management, social simulations, manufacturing applications, electronic auctions, e-institutions, and business to business applications are pervasive and important nowadays. Agent-oriented methodology is an advance in abstractionwhich can be used by software developers to naturally model and develop systems for suchapplications. In general, with respect to design methodologies, what it may be important tostress is that control structures should be added at later stages of design, in a natural top-downmanner going from speciļ¬cations to implementations, by reļ¬nement. Too much detail (be itfor the sake of efļ¬ciency) in speciļ¬cations often turns out to be harmful. To paraphrase D.E.Knuth, āPremature optimization is the root of all evilā (quoted in āThe Unix ProgrammingEnvironmentā by Kernighan and Pine, p. 91).The aim of this thesis is to adapt formal techniques to the agent-oriented methodologyinto an executable theory of reļ¬nement. The justiļ¬cation for doing so is to provide correctagent-based software by design. The underlying logical framework of the theory we proposeis based on rewriting logic, thus the theory is executable in the same sense as rewriting logicis. The storyline is as follows. We ļ¬rst motivate and explain constituting elements of agentlanguages chosen to represent both abstract and concrete levels of design. We then proposea deļ¬nition of reļ¬nement between agents written in such languages. This notion of reļ¬nement ensures that concrete agents are correct with respect to the abstract ones. The advantageof the deļ¬nition is that it easily leads to formulating a proof technique for reļ¬nement viathe classical notion of simulation. This makes it possible to effectively verify reļ¬nement bymodel-checking. Additionally, we propose a weakest precondition calculus as a deductivemethod based on assertions which allow to prove correctness of inļ¬nite state agents. Wegeneralise the reļ¬nement relation from single agents to multi-agent systems in order to ensure that concrete multi-agent systems reļ¬ne their abstractions. We see multi-agent systemsas collections of coordinated agents, and we consider coordination artefacts as being basedeither on actions or on normative rules. We integrate these two orthogonal coordinationmechanisms within the same reļ¬nement theory extended to a timed framework. Finally, wediscuss implementation aspects.LEI Universiteit LeidenFoundations of Software Technolog
Formal methods and tools for the development of distributed and real time systems : Esprit Project 3096 (SPEC)
The Basic Research Action No. 3096, Formal Methods snd Tools for the Development of Distributed and Real Time Systems, is funded in the Area of Computer Science, under the ESPRIT Programme of the European Community. The coordinating institution is the Department of Computing Science, Eindhoven University of Technology, and the participating Institutions are the Institute of Computer Science of Crete. the Swedish Institute of Computer Science, the Programmimg Research Group of the University of Oxford, and the Computer Science Departments of the University of Manchester, Imperial
College. Weizmann Institute of Science, Eindhoven University of Technology, IMAG Grenoble. Catholic University of Nijmegen, and the University of Liege. This document contains the synopsis. and part of the sections on objectives and area of advance, on baseline and rationale, on research goals, and on organisation of the action, as contained in the original proposal, submitted June, 198S. The section on the state of the art (18 pages) and the full list of references (21 pages) of the original proposal have been deleted because of limitation of available space
The use of computer-interpretable clinical guidelines to manage care complexities of patients with multimorbid conditions : a review
Clinical practice guidelines (CPGs) document evidence-based information and recommendations on treatment and management of conditions. CPGs usually focus on management of a single condition; however, in many cases a patient will be at the centre of multiple health conditions (multimorbidity). Multiple CPGs need to be followed in parallel, each managing a separate condition, which often results in instructions that may interact with each other, such as conflicts in medication. Furthermore, the impetus to deliver customised care based on patient-specific information, results in the need to be able to offer guidelines in an integrated manner, identifying and managing their interactions. In recent years, CPGs have been formatted as computer-interpretable guidelines (CIGs). This enables developing CIG-driven clinical decision support systems (CDSSs), which allow the development of IT applications that contribute to the systematic and reliable management of multiple guidelines. This study focuses on understanding the use of CIG-based CDSSs, in order to manage care complexities of patients with multimorbidity. The literature between 2011 and 2017 is reviewed, which covers: (a) the challenges and barriers in the care of multimorbid patients, (b) the role of CIGs in CDSS augmented delivery of care, and (c) the approaches to alleviating care complexities of multimorbid patients. Generating integrated care plans, detecting and resolving adverse interactions between treatments and medications, dealing with temporal constraints in care steps, supporting patient-caregiver shared decision making and maintaining the continuity of care are some of the approaches that are enabled using a CIG-based CDSS
Modelling Mutual Exclusion in a Process Algebra with Time-outs
I show that in a standard process algebra extended with time-outs one can
correctly model mutual exclusion in such a way that starvation-freedom holds
without assuming fairness or justness, even when one makes the problem more
challenging by assuming memory accesses to be atomic. This can be achieved only
when dropping the requirement of speed independence.Comment: arXiv admin note: text overlap with arXiv:2008.1335
Fuzzy approach to construction activity estimation
Past experience has shown that variations in production rate value for the same work item
is attributed to a wide range of factors. The relationships between these factors and the
production rates are often very complex. It is impossible to describe an exact mathematical
causal relationship between the qualitative factors(QF) and production rates. Various
subjective approaches have been attempted to quantify the uncertainties contained in these
causal relationships. This thesis presents one such approach by adopting a fuzzy set theory
in conjunction with a fuzzy rule based system that could improve the quantification of the
qualitative factors in estimating construction activity durations and costs.
A method to generate a Standard Activity Unit Rate(SAUR) is presented. A construction
activity can be defined by combining the Design Breakdown Structure, Trade Breakdown
Structure and Work Section Breakdown Structure. By establishing the data structure of
an activity, it is possible to synthesis the SAUR from published estimating sources in a
systematic way. After the SAUR is defined, it is then used as a standard value from which
an appropriate Activity Unit Rate(AUR) can be determined.
A proto-type fuzzy rule based system called 'Fuzzy Activity Unit Rate Analyser(FAURA)'
was developed to formalise a systematic framework for the QF quantification process in determining the most likely activity duration/cost. The compatibility measurement method
proposed by Nafarieh and Keller has been applied as an inference strategy for FAURA. A
computer program was developed to implement FAURA using Turbo Prolog.
FAURA was tested and analysed by using a hypothetical bricklayer's activity in
conjunction with five major QF as the input variables. The results produced by FAURA
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show that it can be applied usefully to overcome many of the problems encountered in the
QF quantification process. In addition, the analysis shows that a fuzzy rule base approach
provides the means to model and study the variability of AUR.
Although the domain problem of this research was in estimation of activity duration/cost,
the principles and system presented in this study are not limited to this specific area, and
can be applied to a wide range of other disciplines involving uncertainty quantification
problems. Further, this research highlights how the existing subjective methods in activity
duration/cost estimation can be enhanced by utilising fuzzy set theory and fuzzy logic
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