CS 4341 B03 - Solutions HW 1

The Wayback Machne - https://web.archve.org/web/20060905081138/http://web.cs.wp.edu/~cs4341/b03/Projects/Project1/Solutons/soluto…
WPI Worcester Polytechnc Insttute
Computer Scence Department
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CS4341 Introducton to Artfcal Intellgence
Solutons Homework 1 - B 2003
By Prof. Carolna Ruz, Matt Jarvs, and Peter Mardzel
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Homework and Project Goal
Part I. Homework Assgnment
Homework Submsson
Homework Gradng
Homework Solutons
Part II. Project Assgnment
Graduate Credt Problem
Homework and Project Goal:
The goal of Project 1 s to help you understand exactly how dfferent search strateges work. You wll mplement each of nne net search
algorthms. Among the searches are basc searches, heurstcally nformed searches, and optmal searches.
In partcular, the search strateges ncluded n ths project are:
1. Depth 1st search
2. Breadth 1st search
3. Depth-lmted search (depth-lmt = 3)
4. Iteratve deepenng search (show all teratons, not just the teraton that succeeds)

5. Basc Branch-and-bound (= Unform cost search) wth nether Estmated Dstance nor Dynamc Programmng
6. Greedy search (= Best 1st search)
7. A*
8. Hll-clmbng
9. Beam search (w = 2)
The goal of ths project and homework matches the followng Course Objectves:
Learnng to apply course materal (to mprove thnkng, problem solvng, and decson) durng the desgn, mplementaton, and analyss
of computer programs that reason and/or act ntellgently.
Learnng fundamental prncples about and generalzatons of computatonal problem solvng strateges.
Developng creatve capactes for the desgn, mplementaton, and analyss of computer programs that reason and/or act ntellgently.
Learnng to analyze and expermentally evaluate desgns and mplementatons of the ntellgent computer programs, n partcular those
developed durng the course projects.
Ths project conssts of two parts:
1. Part I. A wrtten homework assgnment. Please hand n a HARDcopy of your group solutons at the begnnng of class on Frday Nov. 07.
2. Part II. An mplementaton project. Please submt your group solutons usng the turnn system by Monday, Nov. 10 at 9:00 pm.
Part I. Homework Assgnment:
Suppose that you need to fnd a path between S and G n the followng graph. See the descrpton of ths graph nput format below.
S M 15
S A 1
M G 15
A I 5
A C 2
A B 50
C E 1
C D 10
I J 4
J K 50
J L 5
K L 5
L M 35
#####

S 22
M 14
I 10
J 8
K 6
L 4
E 18
C 16
D 20
A 12
B 24
A pcture of ths graph s ncluded below. Note that the (under)estmated dstance of each node to the goal s ncluded nsde the node. (Specal
thanks to Peter Mardzel for creatng ths pcture).

The homework assgnment s the followng:
For EACH of the search methods above,
1. follow by hand the way n whch the search method seeks a path from S to G. Follow the output specfcatons of the project (Part II)
to show for each method (as your computer program wll do),

1. the lst of nodes n the order n whch they were EXPANDED (not just explored), and
2. the state of the "queue" when the node was expanded.
2. show for each search method the search tree constructed durng the search.
Note that the homework solutons should follow exactly the same conventons as the project descrpton below. In partcular, the chldren of a
node should be consdered ordered n alphabetcal order.
Homework Submsson:
The homework s due at 10 am on Frday November 07, 2003. Please hand n one HARDcopy of your group solutons to the homework
assgnment by the begnnng of the class on Frday, Nov. 07.
Homework Gradng:
Each of the 9 search methods wll be worth 11 ponts. These 11 ponts are dstrbuted n the followng way:
1 ponts for the lst of expanded nodes n the correct order
6 ponts for handlng the queue correctly accordng to the partcular search method
1 pont for expandng the path at the front of the queue
3 pont for storng the chldren of the expanded node n the rght poston n the queue
1 pont for sortng the queue f necessary
1 pont for elmnatng more expensve, redundant paths f necessary
4 ponts for the correct search tree
1 pont for submt the homework (just to make the score sum up to 100 ponts :-)
Total: 100 ponts.
Homework Solutons:
Many thanks to Matt Jarvs for creatng the search trees and to Peter Mardzel for generatng the traces of the queues.