Showing papers by "Qiang Yang published in 1991"
Proceedings Article•
14 Jul 1991TL;DR: This paper provides a crisp formalization of ABSTRIPS-style abstraction, and defines the refinement relationship between solutions at different levels of the abstraction hierarchy, crucial to developing efficient search strategies with this type of hierarchical planning.
Abstract: The purposes of this paper are threefold The first is to provide a crisp formalization of ABSTRIPS-style abstraction, since the lack of such formalizations has made it difficult to ascertain the uses and value of this type of abstraction in previous research Second, we define the refinement relationship between solutions at different levels of the abstraction hierarchy Such definitions are crucial to developing efficient search strategies with this type of hierarchical planning And third, we provide a restriction on the abstraction mapping that provides a criterion for generating useful abstractions
93 citations
Proceedings Article•
24 Aug 1991TL;DR: Working within a semantics for ABSTRIPS-style abstraction, a semantic condition sufficient for guaranteeing its presence in an abstraction hierarchy is developed and a set of sufficient and polynomial-time checkable syntactic conditions that can be used for checking a hierarchy for the downward refinement property are provided.
Abstract: Using abstraction in planning does not guarantee an improvement in search efficiency; it is possible for an abstract planner to display worse performance than one that does not use abstraction. Analysis and experiments have shown that good abstraction hierarchies have, or are close to having, the downward refinement property, whereby, given that a concrete-level solution exists, every abstract solution can be refined to a concrete-level solution without backtracking across abstract levels. Working within a semantics for ABSTRIPS-style abstraction we provide a characterization of the downward refinement property. After discussing its effect on search efficiency, we develop a semantic condition sufficient for guaranteeing its presence in an abstraction hierarchy. Using the semantic condition, we then provide a set of sufficient and polynomial-time checkable syntactic conditions that can be used for checking a hierarchy for the downward refinement property.
40 citations
01 Jan 1991
TL;DR: In this paper, the authors present a nonlinear planning approach for nonlinear linear planning, which they call Nonlinear Nonlinear Planning (NLPNP), which is based on nonlinear geometry.
Abstract: ion in Nonlinear Planning
20 citations
Proceedings Article•
14 Jul 1991TL;DR: This paper provides a quantitative study for plan optimization and presents both optimal and approximate algorithms for finding minimum-cost merged plans and demonstrates that efficient and wellbehaved approximation algorithms are applicable for optimizing general plans with large sizes.
Abstract: Merging operators in a plan can yield significant savings in the cost to execute a plan. Past research in planning has concentrated on handling harmful interactions among plans, but the understanding of positive ones has remained at a qualitative, heuristic level. This paper provides a quantitative study for plan optimization and presents both optimal and approximate algorithms for finding minimum-cost merged plans. With worst and average case complexity analysis and empirical tests, we demonstrate that efficient and wellbehaved approximation algorithms are applicable for optimizing general plans with large sizes.
5 citations