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

What about division and multiply operations, Q. What about division and mul...

Q. What about division and multiply operations? In most of the older computers divisions and multiply were implemented using subtract/add and shift micro-operations. If a digit

What is a kernel shell, A shell is a program that presents an interface to ...

A shell is a program that presents an interface to several operating system functions and services. The shell is so called because it is an outer layer of interface among the user

What is called when network address prefixed by 1110, Network address prefi...

Network address prefixed by 1110 is a? Network address prefixed through 1110 is a multicast address.

Vector-vector instructions-vector processing, Vector-Vector Instructions ...

Vector-Vector Instructions In this type, vector operands are fetched by the vector register and saved in another vector register. These instructions are indicated with the foll

What are the digital certificates of hardware computations, What are the Di...

What are the Digital certificates of hardware computations Digital certificates are highly dependent on hardware computations, it is essential that mechanisms are evolved to i

Determine the disadvantages of fact finding, Determine the Disadvantages of...

Determine the Disadvantages of fact finding -  People are usually uncomfortable being watched and may work in a different way -  What they are watching may not be represent

What is cursor, What is Cursor? Cursor is a database object used by app...

What is Cursor? Cursor is a database object used by applications to manipulate data in a set on a row-by- row basis, instead of the typical SQL commands that operate on all the

What is the future in mq if i have 2+exp, It speeds execution of distribute...

It speeds execution of distributed applications. It runs on dissimilar platforms. It time independent. No loss for msg delivery i.e. guarantee delivery.

Domains of artificial intelligence, The major domains of AI research and...

The major domains of AI research and development. AI applications can be grouped under three major areas cognitive science robotics and natural interfaces though these class

Existential construction - artificial intelligence, The English existential...

The English existential construction involves so-called there-sentences such as these: (1)  There is a dog in the yard (2)  There were no children at the party (3)  There

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