文档介绍：第四部分第四部分基于逻辑的规划方法基于逻辑的规划方法第第 2 2 2 2 章章规划规划 STRIPS STRIPS 规划系统规划系统 描述状态和目标描述状态和目标 向前搜索方法向前搜索方法 递归递归 S T R I P S S T R I P S ? Divide-and-conquer : a heuristic in forward search ? divide the search spac e into islands ? islands: a state descr iption in which one of the conjuncts is sa tisfied ? STRIPS( ?): a proced ure to solve a conjun ctive goal formula ?. 带有运行时条件的计划带有运行时条件的计划 Needed when we generalize the kinds of formulas Needed when we generalize the kinds of formulas allowed in state descriptions. allowed in state descriptions. . . wff wff On(B,A On(B,A ) V ) V On(B,C On(B,C ) ) –– branching branching The system does not know which plan is being generated at The system does not know which plan is being generated at the time. the time. The planning process splits into as many branches as there The planning process splits into as many branches as there are are disjuncts disjuncts that might satisfy operator preconditions. that might satisfy operator preconditions. –– runtime conditionals runtime conditionals Then, at run time when the system encounters a split into two Then, at run time when the system encounters a split into two or more contexts, perceptual processes determine which of or more contexts, perceptual processes determine which of the the disjuncts disjuncts is true. is true. –– . the runtime conditionals here is . the runtime conditionals here is ““ know which know which is true at the is true at the time time ”” Sussman Sussman 异常异常目标条件是目标条件是 O O n(A n(A , B) , B) ∧∧ O O n(B n(B , C) , C) , , The The Sussman Sussman 异异常常? . ? STRIPS selection: On(A,B) ? On(B,C) ? On(A,B) …? Difficult to solve with recursive STRIPS (similar to DF S) ? Solution: BFS ? BFS: computationally infeasible ??“ BFS+Backward Search Methods ” ABCB BAABCB AC goal condition: On(A,B) ? On(B,C) Figure 层次规划层次规划