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

Create a system dynamic model, Easter Island is a small island (about 150 s...

Easter Island is a small island (about 150 square miles in area) in the Pacific Ocean about 2,000 miles from South America. In about 400 AD there was a small population of settlers

Example multi-layer ann with sigmoid units, Example Multi-layer ANN with Si...

Example Multi-layer ANN with Sigmoid Units: However we will concern ourselves here that with ANNs containing only one hidden layer and as this makes describing the backpropaga

What is the working of domain expert, Q. What is the working of domain expe...

Q. What is the working of domain expert? ANSWER: The domain expert is the person who gives the domain expertise in the form of problem-solving strategies.

An example subroutine call, Create your own Subprogram that does *not* use ...

Create your own Subprogram that does *not* use any input parameters. You decide the theme. You should give the pseudocode and an example Subroutine call. Be sure to give an overvie

How the canvas class and the graphics class are linked, A Canvas object giv...

A Canvas object gives access to a Graphics object by its paint() method.

Electric circuit analysis, mmmmmmmmmmmmm mmmmmmm s s s s s s s s s d d d ...

mmmmmmmmmmmmm mmmmmmm s s s s s s s s s d d d d d d d d d d d d d d f f ff g gg g g g g gg r r r rr r w ww w w ww w w

Explain working of digital camera, Q. Explain working of Digital camera? ...

Q. Explain working of Digital camera? A Digital camera is a camera which captures and stores still images and video (Digital Video Cameras) as digital data in place of on photo

Control unit (cu)-array processing, Control Unit (CU)  : Every PEs are unde...

Control Unit (CU)  : Every PEs are under the control of one control unit. CU controls the inter communication among the PEs. There is a local memory of CU also known as CY memory.

Vector processing, Vector Processing  A vector is an ordered set of the...

Vector Processing  A vector is an ordered set of the similar type of scalar data items. The scalar item can be a floating point number, a logical value or an integer. Vector pr

Explain the term - computer aided software engineering, Explain the term - ...

Explain the term - Computer Aided Software Engineering Production of software became much commercial. Software development tools were devised. Concept of Computer Aided Softwar

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