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SHOP and SHOP2 are HTN planning systems that were designed with two goals in mind: to investigate some research issues in automated planning, and to provide some simple, practical planning tools. They are available as freeware, and have developed an active base of users in government laboratories, industrial R&D projects, and academic settings. This paper(More)
This paper describes SiN, a novel case-based planning algorithm that combines conversational case retrieval with generative planning. SiN is provably correct, and can generate plans given an incomplete domain theory by using cases to extend that domain theory. SiN can also reason with imperfect world-state information by incorporing preferences into the(More)
Previous algorithms for learning lexicographic preference models (LPMs) produce a "best guess" LPM that is consistent with the observations. Our approach is more democratic: we do not commit to a single LPM. Instead, we approximate the target using the votes of a <i>collection</i> of consistent LPMs. We present two variations of this method---<i>variable(More)
Despite the fact that thousands of applications manipulate plans, there has been no work to date on managing large databases of plans. In this paper, we first propose a formal model of plan databases. We describe important notions of consistency and coherence for such databases. We then propose a set of operators similar to the relational algebra to query(More)
In this paper we present a formalism for explicitly representing time in HTN planning. Actions can have durations and intermediate effects in this formalism. Methods can specify qualitative and quantitative temporal constraints on decom-positions. Based on this formalism we defined a planning algorithm TimeLine that can produce concurrently executable plans(More)
There are numerous applications where we need to ensure that multiple moving objects are sufficiently far apart. Furthermore, in many moving object domains , there is positional indeterminacy — we are not 100% sure exactly when a given moving object will be at a given location. [Yaman et al., 2004] provided a logic of motion but did not provide algorithms(More)