Hill climbing - artificial intelligence , Basic Computer Science

Assignment Help:

Hill Climbing - artificial intelligence:

As we've seen, in some particular problems, searching the search path from primly to goal state is the point of the exercise. In another problem, the path and the artefact at the end of the path are both important, and we often try to find optimal solutions. For a sure set of problems, the path is immaterial, and finding a suitable artefact is the sole purpose of the search. In these types of cases, it doesn't matter whether our agent searches a path for ten or thousand steps, so long as it finds a solution in the end.

Take an example of the 8-queens problem, where the job is to find an arrangement of 8 queens on a chess board likewise that no one can "take" another (one queen can take another if it's on the same horizontal, vertical or diagonal line). A solution to this problem is:

 

287_Hill Climbing.png

One way to describe this problem is with states where there are many queens (1 to 8) on the board, and an action is to add a queen in that kind of way that it can't take another. Depending on your method, you can find that this search requires much back-tracking, for example , towards the end, you find that you  just simply can't put the last queens on anywhere, so you have to move one of the queens you put down earlier (you go back-up the search tree).

Another way of specifying the problem is that the states are boards with eight queens already on them, and a stroke is a movement of one of the queens. In this particular case, our agent might be use an evaluation function and do hill climbing. i.e., it measures the number of pairs of queens where one can take the other and only moves a queen if that movement reduces the number of pairs. When there is an option of movements both resulting in same amount of decrease, the agent may select one arbitrarily from the option. In the 8-queens problem, there are just 8 * 56 = 448 probable ways to move one queen, so our agent only has to calculate the evaluation function 448 times at each stage. If it just selected moves where the situation with respect to the evaluation function improves, it is doing hill climbing (or gradient descent if it's better to think of the agent going downhill rather than uphill).

A general problem with this search method is local maxima: the search has not yet reached a solution, but it can just go downhill in terms of the evaluation function. I.e., we might get to the stage where only 2 queens may take each other, but moving any queen increases this number to at least three. In such a cases, the agent may do a random re-start whereby they randomly choose a state to start the complete process from again. This search scheme has the appeal of never requiring storing more than one state at any one time (the part of the hill the agent is on). Russell and Norvig make the analogy that this kind of search is like trying to climb Everest in the fog with amnesia, but they do concede that it is frequently the search strategy of option for some industrial problems.Local/Global Maxima/Minima are represented in the diagram below:

899_Hill Climbing1.png


Related Discussions:- Hill climbing - artificial intelligence

Analogue computers, ANALOGUE COMPUTERS A computer is basically a proble...

ANALOGUE COMPUTERS A computer is basically a problem-solving device. In aircraft radio systems the problem to be solved is concerned with navigation, in that given certain inf

Cryptography, For which X,Y in {o, O, Theta, Omega, omega}, do the relation...

For which X,Y in {o, O, Theta, Omega, omega}, do the relationships t(n)+t''(n) = X(min(t(n),t''(n))) and t(n)+t''(n) = Y(max(t(n),t''(n))) hold for all t,t'' such that t(n),t''(n)

Explain data transfer and arithmetic operations, Question 1 Convert the fo...

Question 1 Convert the following binary numbers to decimal 101110 1110101 110110 101010 110010 Question 2 Explain CPU module and types of transfers betwe

Explain the functions of alu, Question 1 Write down the Booth's Multiplica...

Question 1 Write down the Booth's Multiplication Algorithm. Justify the Booth's Multiplication Algorithm Question 2 Explain the functions of ALU Question 3 Define the term ins

Power point, how to start ms power point

how to start ms power point

Data processing, Data Processing In any computer-based system, d...

Data Processing In any computer-based system, data storage and retrieval plays an important role. Data storage involves decision about the encoding of data, assignment o

Html, a program to create htmlpage

a program to create htmlpage

Super computers, Super Computers: The specialised demands and requirem...

Super Computers: The specialised demands and requirements of science, industry and military have led to the creation of powerful super computers. For numerically intensive com

Obtain the truth table and a boolean expression, Problem 1. Convert the...

Problem 1. Convert the following number system 12.34 (8) to binary number system 23BC.0A (16) to decimal number system 456.012 (16) to Octal number system 123

Describe counting instructions, They are used to reduce or enlarge the cont...

They are used to reduce or enlarge the content of the counters. DEC INC DEC INSTRUCTION Idea: To diminish the operator. Syntax: DEC destiny This action subtracts 1 from the destiny

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd