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X-WR-CALNAME:Computational Optimisation Group
X-ORIGINAL-URL:http://optimisation.doc.ic.ac.uk
X-WR-CALDESC:Events for Computational Optimisation Group
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DTSTART:20130101T000000
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BEGIN:VEVENT
DTSTART;TZID=UTC:20140115T151500
DTEND;TZID=UTC:20140115T151500
DTSTAMP:20260419T094105
CREATED:20170124T102140Z
LAST-MODIFIED:20170124T102140Z
UID:572-1389798900-1389798900@optimisation.doc.ic.ac.uk
SUMMARY:Seminar: Numerical Aggregation of Trust Evidence: Its Analysis and Optimisation
DESCRIPTION:Title: Numerical Aggregation of Trust Evidence: Its Analysis and OptimisationSpeaker: Prof. Michael Huth and Dr. Jim Huan-Pu KuoAffiliation: Department of Computing – Imperial College LondonLocation: Room 217 Huxley BuildingTime: 3:15pm \nAbstract. We have designed a language in which modellers can specify trust and distrust signals that\, in their presence\, generate a numerical score\, and where such scores can be combined with aggregation operators to express risk postures for trust-mediated interactions in IT systems. Signals may stem from heterogenous sources such as geographical information\, reputation\, and threat levels. Aggregated scores then inform decisions by generating conditions that compare scores to threshold values of trustworthiness. We developed a generic approach to analysing such conditions by automatically converting them into code for the Satisfiability Modulo Theory solver Z3 from Microsoft Research. This allows us to automatically analyse\, e.g.\, whether a condition is sensitive to the increase of a trustworthiness threshold by a specified amount. We would now like to understand better whether such analysis questions can be expressed in known models as used in optimisation. For example\, let a condition say that the aggregated trust score has to be above 0.5. Solvers such as Z3 seem to be unable to compute the largest interval containing 0.5 such that all values of that interval could be chosen as trustworthiness threshold without changing the behaviour of the condition. On the other hand\, Z3 is perfect for reflecting logical dependencies or inconsistencies between (dis)trust signals that occur in such conditions and are quantifier-free formulas of first-order logic. A prototype implementation of the tool is available at http://delight.doc.ic.ac.uk:55555 \nAbout the speaker.
URL:http://optimisation.doc.ic.ac.uk/event/seminar-numerical-aggregation-of-trust-evidence-its-analysis-and-optimisation/
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BEGIN:VEVENT
DTSTART;TZID=UTC:20140128T140000
DTEND;TZID=UTC:20140128T140000
DTSTAMP:20260419T094105
CREATED:20170124T102140Z
LAST-MODIFIED:20170124T102140Z
UID:571-1390917600-1390917600@optimisation.doc.ic.ac.uk
SUMMARY:Seminar: Revolutionizing Airline Planning & Scheduling with the Invention of Unified Optimization
DESCRIPTION:Title: Revolutionizing Airline Planning & Scheduling with the Invention of Unified OptimizationSpeaker: Dr. Nikolaos PapadakosAffiliation: Decisal LtdLocation: Room 345 Huxley BuildingTime: 2:00pm \nAbstract. Airline planning and scheduling are complex mixed integer problems. To reduce complexity each of them has traditionally been split into stages. For example\, scheduling is split into fleet assignment\, aircraft scheduling\, and crew scheduling\, which are solved sequentially one after the other. These stages are\, however\, interdependent and airlines have to deal with under-optimal results and constraint violations. Decisal is the company that invented algorithms for Unified Optimization of these stages\, greatly improving profit optimization and constraint satisfaction. The methodology for Unified Optimization includes several advancements of Benders Decomposition. Finally\, in some cases\, both the Benders master problem and the Benders subproblem are made of improved column generation algorithms. \nAbout the speaker. Dr Nikos (Nikolaos) Papadakos is the research and development director of Decisal. Prior to that he worked as a research associate at Imperial College London where he also received a PhD in operations research and an MSc in advanced computing. He also holds a BSc in mathematics from the University of Athens. Finally\, his work experience includes the Bank of Attica and Biomex Epe\, in software development\, sales\, and customer support.
URL:http://optimisation.doc.ic.ac.uk/event/seminar-revolutionizing-airline-planning-scheduling-with-the-invention-of-unified-optimization/
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