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

PADOVAN STRING, write a program that counts the number of occurrences of th...

write a program that counts the number of occurrences of the string in the n-th Padovan string P(n)

For what an append query be used, For what an append query be used? It ...

For what an append query be used? It is simple to append records from one table to another using an append query. There is no requirement for the tables to have the similar num

Data bus is bidirectional, Why address bus is unidirectional and data bus i...

Why address bus is unidirectional and data bus is bidirectional? Ans) Because there is no require address transaction among processor and peripheral device but data bus is req

Why did my jdbc code throw a rollback sqlexception, Your JDBC code may thro...

Your JDBC code may throw the following exception: "The coordinator has rolled back the transaction.No further JDBC access is permitted within this transaction." The WebLogic

Can we use flow logic control key words in abap/4, Can we use flow logic co...

Can we use flow logic control key words in ABAP/4 and vice-versa The flow control  of a dynpro having os a few statements that syntactically ressemble ABAP/4  statements .Thou

How to make a datapool, When producing a datapool, you state the kinds of d...

When producing a datapool, you state the kinds of data (called data types) that the script will send for example, customer names, addresses, and unique order numbers or product nam

Explain step by step switching system with neat diagram, With the help of a...

With the help of a neat diagram explain a step by step switching system. Configuration of a step by step switching system: A step by step switching system may be constr

Size of scripts and libraries, Main script section ("Sub Main .. End Sub) a...

Main script section ("Sub Main .. End Sub) and function bodies should fit within an A4-page (approx. two monitor-pages). If the code doesn't fit it is a candidate to do more decoup

Explain normans execution-evaluation cycle model, Question 1: (a) How ...

Question 1: (a) How would you explain human reasoning? (b) Explain the different types of human reasoning? Question 2: (a) What are the computational factors affec

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