Semantics for HTN Planning

(Also cross-referenced as ISR-TR-95-9) One big obstacle to understanding the nature of hierarchical task network (HTN) planning has been the lack of a clear theoretical framework. In particular, no one has yet presented a clear and concise HTN algorithm that is sound and complete. In this paper, we present a formal syntax and semantics for HTN planning. Based on this syntax and semantics, we are able to define an algorithm for HTN planning and prove it sound and complete. We also develop several definitions of expressivity for planning languages and prove that HTN Planning is strictly more expressive than STRIPS-style planning according to those definitions. (Also cross-referenced as UMIACS-TR-94-31

Complexity Results for HTN Planning

(Also cross-referenced as ISR-TR-95-10) Most practical work on AI planning systems during the last fifteen years has been based on hierarchical task network (HTN) decomposition, but until now, there has been very little analytical work on the properties of HTN planners. This paper describes how the complexity of HTN planning varies with various conditions on the task networks, and how it compares to STRIPS-style planning. (Also cross-referenced as UMIACS-TR-94-32

Complexity, Decidability and Undecidability Results for Domain-Independent Planning: A Detailed Analysis

In this paper, we examine how the complexity of domain-independent planning with STRIPS-like operators depends on the nature of the planning operators. We show conditions under which plannning is decidable and undecidable. Our results on this topic solve an open problem posed by Chapman [4], and clear up some difficulties with his undecidability theorems. For those cases where planning is decidable, we show how the time complexity varies depending on a wide variety of conditions: . whether or not function symbols are allowed; . whether or not delete lists are a]]owed; . whether or not negative preconditions are allowed; . whether or not the predicates are restricted to be propositional(i.e., 0-ary); . whether the planning operators are given as part of the input to the planning prob]em, or instead are fixed in advance. (Also cross-referenced as UMIACS-TR-91-154

Complexity, Decidability and Undecidability Results for Domain-Independent Planning

In this paper, we examine how the complexity of domain-independent planning with STRIPS-style operators depends on the nature of the planning operators. We sho

Complexity, decidability and undecidability results for domain-independent planning

In this paper, we examine how the complexity of domain-independent planning with STRIPS-style operators depends on the nature of the planning operators. We show conditions under which planning is decidable and undecidable. Our results on this topic solve an open problem posed by Chapman [5], and clear up some difficulties with his undecidability theorems. For those cases where planning is decidable, we explain how the time complexity varies depending on a wide variety of conditions: • whether or not function symbols are allowed; • whether or not delete lists are allowed; • whether or not negative preconditions are allowed; • whether or not the predicates are restricted to be propositional (i.e., 0-ary); • whether the planning operators are given as part of the input to the planning problem, or instead are fixed in advance. • whether or not the operators can have conditional effects

Use of fuzzy optimization and linear goal programming approaches in urban bus lines organization

Determination of bus stop locations and bus stop frequencies are important issues in public transportation planning. This study analyzes the relationships among demand, travel time, bus stop locations, frequency, fleet size and passenger capacity parameters and develops models for bus stop locations and bus service frequency using fuzzy linear programming and linear goal programming approaches. The models are microscopic and applied to determine the bus stop locations and bus service frequency in the city of Izmir, Turkey, where 26 bus routes pass through two stops in the center city. The fuzzy optimization model minimizes the passenger access time and in-vehicle travel time. The reduction of the values of the bus service frequency and time parameters derived by the two proposed models are validated by a cost function. Encouraging results are obtained. © Springer International Publishing Switzerland 2014

Sutured ECH is a natural invariant

We show that sutured embedded contact homology is a natural invariant of sutured contact 3-manifolds which can potentially detect some of the topology of the space of contact structures on a 3-manifold with boundary. The appendix, by C. H. Taubes, proves a compactness result for the completion of a sutured contact 3-manifold in the context of Seiberg-Witten Floer homology, which enables us to complete the proof of naturality

HTN planning: Complexity and expressivity

Most practical work on AI planning systems during the last fteen years has been based on hierarchical task network (HTN) decomposition, but until now, there has been very little analytical work on the properties of HTN planners. This paper describes how the complexity of HTN planning varies with various conditions on the task networks