Arc consistency, Computer Engineering

Assignment Help:

Arc Consistency:

There have been many advances in how constraint solvers search for solutions (remember this means an assignment of a value to each variable in such a way thatno constraint is broken). We look first at a pre-processing step which can greatly improve efficiency by pruning the search space, namely arc-consistency. Following this, we'll look at two search methods, backtracking and forward checking which keep assigning values to variables until a solution is found. Finally, we'll look at some heuristics for improving the efficiency of the solver, namely how to order the choosing of the variables, and how to order the assigning of the values to variables. 

The pre-processing routine for bianry constraints known as  arc-consistency involves calling a pair (xi, xj) an arc and noting that this is an ordered pair, i.e., it is not the same as (xj, xi). Each arc is associated with a single constraint Cij, which constrains variables xi  and xj. We say that the arc (xi, xj) is  consistent  if, for all values a in Di, there is a value b in Dj  such that the assignment xi=a and xj=b satisfies constraint Cij. Note that (xi, xj) being consistent doesn't necessarily mean that (xj,xi) is also consistent. To use this in a pre-processing way, we take every pair of variables and make it arc-consistent. That is, we take each pair (xi,xj) and remove variables from Di  which make it inconsistent, until it becomes consistent. This effectively removes values from the domain of variables, hence prunes the search space and makes it likely that the solver will succeed (or fail to find a solution) more quickly.


Related Discussions:- Arc consistency

Data Warehousing Job Scheduling, 1) Define a job scheduling strategy that w...

1) Define a job scheduling strategy that will meet business requirement of reporting availability by 6am CST for the following cubes? Show the job scheduling dependencies in a pict

How putchar function is used within a c program, How putchar function is us...

How putchar function is used within a C Program ? The following program reads each character in the first line of input entered at the terminal's keyboard. It uses putchar to d

What is meant by common control, What is meant by common control? In se...

What is meant by common control? In several switching systems, the control subsystem may be an integral part of the switching network itself. This system is termed as direct co

What is a path name, What is a path name?  A pathname is the path from ...

What is a path name?  A pathname is the path from the root by all subdirectories to a specified file. In a two-level directory structure a user name and a file name describe a

Using the editor or debugger, Write a script that will read from a file x a...

Write a script that will read from a file x and y data points in the following format: x   0    y  1 x  1.3  y  2.2 x  2.2  y  6 x  3.4  y  7.4 The format of each line in the

Explain the term - instruction execution, Explain the term - Instruction ex...

Explain the term - Instruction execution We  know  that  the  fundamental  function  performed  by  a  computer  is  the  execution  of  program. The program that is to be exec

Demonstration of sorting problem, Q. Demonstration of sorting problem? ...

Q. Demonstration of sorting problem? The term sorting implies organising elements of a provided set of elements in a specific order i.e. descending order / ascending order / al

Conversion of decimal number 82.67 to its binary equivalent, Conversion of ...

Conversion of Decimal number 82.67 to its Binary Equivalent Ans. Firstly see the integer part 82 and determine its binary equivalent  as The Binary equivalent is (101001

Computer engineering designing, How the production of metal contributes to ...

How the production of metal contributes to computer engineering designing?

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