week8.2-s08 - Happy Spring Break Scheduling The State of...

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Happy Spring Break!
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I ntegrating Planning & Scheduling Subbarao Kambhampati Scheduling: The State of the Art Integrating Planning & Scheduling Overview Why integrate planning and scheduling? Planning: The state of the art Scheduling: The state of the art Integrating Planning and Scheduling
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I ntegrating Planning & Scheduling Subbarao Kambhampati Planning Initial state & a set of Goals, A library of actions » Preconditions/effects Discrete/Continuous » Resource requirements Synthesize a sequence of actions capable of satisfying goals I = initial state G = goal state O i (prec) (effects) [ ] O i O j O k O m [ G ] Planning vs. Scheduling Scheduling Set of jobs (may have of tasks in some (partial) order) Temporal constraints on jobs » EST, LFT, Duration Contention constraints » Each task can be done on a subset of machines Find start times for jobs that are optimal (wrt make-spans, resource consumption etc) T2 T1 EST LFT Dur A Continuum -- Research into planning and scheduling methods has largely been de-coupled Resource Reasoning Causal Reasoning portant: ACTION prec/Effect models not needed
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I ntegrating Planning & Scheduling Subbarao Kambhampati Why separate scheduling from planning? Clearly, Scheduling can be seen as a sub-problem of temporal planning (unlike scheduling, planning also contains action selection). So, why separate it? Reasons from automated planning point of view » If multiple agents make their plans and execute them on central resources, separating resource scheduling from individual agent planning makes sense » Certain resource constraints may not be available at planning time and so the planner has to postpone them to a separate scheduling phase » Even if a single agent is doing planning, it may be worth separating causal reasoning and resource reasoning Such “de-coupling” improves efficiency, but at the expense of global optimality guarantees Reasons from “real world practice” point of view » Historically, in many domains, action selection and automated causal reasoning was out of question (either because it couldn’t be modeled and solved or because the humans didn’t want to delegate it to automated methods » So, the only computer support for planning activity was given for resource scheduling (humans make plans, and schedulers do resource allocation)
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I ntegrating Planning & Scheduling Subbarao Kambhampati Simple job-shop Scheduling: Brief Overview Jobshop scheduling Set of jobs » Each job consists of tasks in some (partial) order Temporal constraints on jobs » Sequencing constraints » Release times, deadlines, durations EST, LFT, Duration Contention/capacity constraints »
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This note was uploaded on 05/07/2011 for the course INDUSTRIAL IE 208 taught by Professor Serolbulkan during the Fall '11 term at Marmara Üniversitesi.

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week8.2-s08 - Happy Spring Break Scheduling The State of...

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