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

Find the generating function, Find the generating function to denote the nu...

Find the generating function to denote the number of ways the sum 9 can be acquired while 2 distinguishable fair dice are tossed and the first shows an even number and the second s

Assembly 8086 program that computes the minimum and maximum, Write a progra...

Write a program that computes the minimum and maximum of elements in an array in Assembly 8086.

Explain working of intranet, Intranets are mainly "small" Internets. They u...

Intranets are mainly "small" Internets. They use same network facilities that Internet does, though access is restricted to a limited sphere. For example, a company can set up an i

Define how ptrace is used by debuggers, State how Shared Memory is used for...

State how Shared Memory is used for inter process communication. Define how ptrace is used by debuggers.  What are modules? Explain how data mapping takes place among modules

What is the use of system.xml.xlinq.dll, System.XML.XLinq.dll has classes t...

System.XML.XLinq.dll has classes to provide functionality to use LINQ with XML.

How can we write an interrupt servicing routine, Q. How can we write an Int...

Q. How can we write an Interrupt Servicing Routine? The following are the fundamentalthough rigid sequence of steps: 1.  Save the system context (flags,registers etc. which

Computer graphics, what is boundary filling explain with example

what is boundary filling explain with example

What is cache memory, Q. What is Cache Memory? Cache memory is a very f...

Q. What is Cache Memory? Cache memory is a very fast and small memory between CPU and main memory whose access time is closer to processing speed of CPU. It behaves as a high-s

Fixed arithmetic pipelines, Fixed Arithmetic pipelines  We obtain the e...

Fixed Arithmetic pipelines  We obtain the example of multiplication of fixed numbers. The Two fixed-point numbers are added by the ALU using shift and add operations. This sequ

What are the graphics adapters, Graphics adapters: Video card converts...

Graphics adapters: Video card converts digital output from computer into an analog video signal and transmits the signal through a cable to monitor also known as a graphics ca

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