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

Structured analysis and design approach, Q. Structured Analysis and Design ...

Q. Structured Analysis and Design Approach? The objective of structured system analysis and design is to reduce maintenance time as well as effort. Modeling is the act of drawi

Determine the features of keyboards, Determine the features of keyboards ...

Determine the features of keyboards Common features on general-purpose keyboards are cursor-control keys. Functions keys are used to enter frequently used operations in a singl

What is self reference, What is self reference?  The Turing machine tha...

What is self reference?  The Turing machine that ignores its input and prints out a copy of its own description,   we call this as SELF. There is a computable function q: €*€*,

How do you ensure that our records are scanned accurately, How do you ensur...

How do you ensure that our records are scanned accurately? Not only do we have a highly trained and capable staff, we also have quality controls in place to make sure your reco

Describe the limitation of fat16, Q. Describe the Limitation of FAT16? ...

Q. Describe the Limitation of FAT16? DOS designers decided to use clusters with as a minimum four sectors in them (so a cluster size of at least 2KB) for all FAT16 hard disks.

How to manage the web based projects, How to manage the web based projects?...

How to manage the web based projects? Many project management applications contain additional functions useful in the management of group projects. These features may contain g

Show the mips addressing modes, Q. Show the MIPS Addressing Modes? MIP...

Q. Show the MIPS Addressing Modes? MIPS Addressing Modes MIPS employs various addressing modes: 1. Uses Register as well asimmediate addressing modes for operations.

Define hyperlinks, Q. Define Hyperlinks? Hyperlinks, or links are one o...

Q. Define Hyperlinks? Hyperlinks, or links are one of the most significant characteristics of web pages. A link moves us from current page to a destination which is specified i

Provide a diagrammatic interpretation of the hardware stack, a) Prototype ...

a) Prototype a macro known AP which takes 4 integer parameters n (number of terms), a (first term), l (last term) and Sum (sum of n terms), provided that: Sum = (a+l)*n/2 b)

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