Effective branching rate - heuristic searches, Computer Engineering

Effective Branching Rate:

Assessing heuristic functions is an important part of "AI" research: a particular heuristic function may sound such a good idea, but in practice give no discernible increase in the quality of the search. Search quality can be estimated experimentally in terms of the output from the search, so by using various measures such as the effective branching rate. Let suppose a particular problem P has been solved by search strategy S by expanding N nodes, and the solution play at depth D in the space. Then the effective branching rate of S for P is calculated by comparing S just to a uniform search U. The other example of a uniform search is a breadth first search where the number of branches from any node is always the same (as in our baby naming example). After that we suppose the (uniform) branching rate of U is like that, on the exhausting its search to depth D, it too would have expanded exactly N nodes. That should be imagined branching rate, written b*, is the effective branching rate of S and is calculated thus:

N = 1 + b* + (b*)2 + ... + (b*)D.

Rearranging this equation will give a proper value for b*. For example if we considered that we taken from Russell and Norvig rule, suppose S finds a solution at depth 5 having expanded 52 nodes. As in the above this case:

52 = 1 + b* + (b*)2 + ... + (b*)5.

and it turns out that b*=1.91. To calculate this, we can use the very well known mathematical character:

362_Effective Branching Rate.png
This enables us to write a polynomial for which b* is a zero, and we can solve this using numerical techniques like Newton's method.
It is normally the case that the effective branching rate of a search strategy is similar over all the problems. It is may be used for, so that it is acceptable to average b* over a small set of problems to give a valid account. If there is a heuristic search has a branching rate near to 1, then this is a good sign. We state that one heuristic function h1 dominates another h2 if the search using h1 always has a lower effective branching rate than h2. Having a lower effective branching rate is clearly desirable because it means a quicker search.

Posted Date: 1/10/2013 4:38:13 AM | Location : United States

Related Discussions:- Effective branching rate - heuristic searches, Assignment Help, Ask Question on Effective branching rate - heuristic searches, Get Answer, Expert's Help, Effective branching rate - heuristic searches Discussions

Write discussion on Effective branching rate - heuristic searches
Your posts are moderated
Related Questions
What is finest way to get a reference to the viewport from anywhere in the code? Ans) You can use refs config to set a reference on the Application/Controllers

What is the use of digital switch? Digital switch: This is a device which handles digital signals generated at or passed via a telephone company’s central office further

Design a counter modulo 4 (sequential circuit with two flip-flops and one input U) which work like that: 1. When U=0, the state of the flip-flop does not change. 2. Whe

Define the term package- object oriented modeling A package is a common purpose mechanism for organising elements into groups. Package can also contain other packages. The no

What is a shift register? Can a shift register be used as a counter? If yes, explain how?     Ans: Shift Register: A register wherein data gets shifted towards left or right

Q. What do you mean by Lock Synchronization? Lock Synchronization: In this method contents of an atom are updated by requester process and sole access is granted before atomic

Propositional Logic: This is a fairly restrictive logic, that allows us to be write sentences about ¬propositions - statements about the world - that can either be true or

advantages and disadvantages of northwest corner method and least cost method

Discuss the CSMA/CD and CSMA/CA protocols. CSMA/CD: this is an access method used mainly with LANs configured in a bus topology. Along with CSMA/CD, any station (node) can se

the 68000 has rich of addressing mode . it concerned with the way data is accessed . identify the destion addressing mode for EXG D0, A2