# ex1 - CS221 Exercise Set#1 1 CS 221 Autumn 2007 Exercise...

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Unformatted text preview: CS221 Exercise Set #1 1 CS 221, Autumn 2007 Exercise Set #1: Search and Motion Planning Handout #4 1. In this problem, you will implement different search strategies on a given search tree. The start state is denoted by S and the goal state by G . Number the nodes in the tree according to the order in which they will be expanded . (Recall that a node is expanded when it is removed from the list of nodes, checked for “goalness”, and its children are inserted into the list.) Do not number a node if it is not expanded in the search. Assume that the children of a node are inserted into the list in left to right order, and that nodes of equal priority are extracted from the list in FIFO order. Write your answers directly on the trees provided below. (a) Breadth First Search. G S CS221 Exercise Set #1 2 (b) Depth First Search. G S (c) Iterative Deepening. (Hint: Here, a node may have multiple labels.) G S CS221 Exercise Set #1 3 (d) Uniform Cost Search, where the costs of the edges are as specified on the tree. Here, also write down the g-value of the different nodes in the tree. You only need to write down g-values for nodes that are inserted into the list. g= g= g= g= g= g= g= g= g= g= g= g= g= g= g= g= g= 1 g= 2 1 2 2 2 3 2 1 3 1 2 1 2 3 3 2 S G CS221 Exercise Set #1 4 2. Describe a search space in which iterative deepening search performs much worse than depth-first search. 3. This problem explores the issues involved in search space formulation. Consider the task of scheduling n final exams in Gates Building. For each exam, we have the list of students that must take the exam. Our task is to assign each exam to a time slot. More than one exam may be assigned to a time slot, but there are two constraints: no student will be required to take two exams at the same time, and at most k exams may be scheduled in a time slot (since only k rooms are available for this purpose). (a) Provide a detailed representation of your search space. Your description must be precise, i.e., you should provide an exact specification of the components of the state description (state space, initial state, operators, goal test), of the constraints under which each operator can be applied, and of the effects of each operator on the state...
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## This note was uploaded on 11/30/2009 for the course CS 221 taught by Professor Koller,ng during the Winter '09 term at Stanford.

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ex1 - CS221 Exercise Set#1 1 CS 221 Autumn 2007 Exercise...

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