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**Unformatted text preview: **ICS 171, Summer 2000: Lecture 3 Homework
Stephen D. Bay August 15, 2000
Due: August 22, 2000 1 Consider the following graph representing the state space and operators of a navigation
problem:
5 A 3 7 S 2 B 1 C 5 2 H 4 4 4 3 2 E 1 1 F G 3 D 2 0 2 4 The path cost is shown by the number on the links; the heuristic evaluation is shown by the number in the box. When placing expanded child nodes on a queue, assume that the child nodes are placed in alphabetical order i.e. if node S is expanded the queue will be: A B Assume that we never generate child nodes that appear as ancestors of the current node in the search tree. a What is the order that best rst search will expand the nodes? b What is the order that uniform cost search will expand the nodes? c What is the order that A* search will expand the nodes? d What is the order that IDA* search will expand the nodes? e What is the order that hill-climbing search will expand the nodes? 1 2 What will happen in best rst search if we set = , ? 3 Question 4.2, parts b, c, and d in the course text Russell & Norvig, page 118. 4 Suppose that 1 and 2 are admissible heuristics. Which of the following are admissible?
h n g n h h 1 + 2 2
h h 2 max h1 h1 ; h2 5 If
F and 2 are admissible heuristics, which is the better method of combining them: = max 1 2 or = 1 + 2 2? Explain.
h1 h h ;h G h h = 2 ...

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