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

E- commerce technology and web design, In this assignment, you are required...

In this assignment, you are required to develop part of a B2C e-Commerce site which is an online movie reservation system for a multiplex theatre. Through the developed site, the u

When should the method invokelater() be used, This method is used to make s...

This method is used to make sure that Swing components are updated by the event-dispatching thread.

Determine frame time and propagation time in a lan, Maximum channel utiliza...

Maximum channel utilization in a LAN is defined by frame time (t f ) and propagation time (t p ). It is defined by (A) t p /t f (B) t f /t p  (C) 1 + (t f /t p )

Illustrate the logical view of a system, Illustrate the Logical view of a s...

Illustrate the Logical view of a system The Logical view of a system serves to describe existence and meaning of key abstractions and mechanism which form problem space, or wh

How to design a sequential circuit, A sequential circuit is signified by a ...

A sequential circuit is signified by a time sequence of external inputs, external outputs and internal flip-flop binary states. So firstly a state diagram and state table is used t

Meaning of every field in mips instruction, Q. Meaning of every field in MI...

Q. Meaning of every field in MIPS instruction? The meaning of every field in MIPS instruction is given below: op: operation code or opcode rs: First register source

Determine the decimal equivalent of octal number, The number 140 in octal i...

The number 140 in octal is equivalent to decimal number ? Ans. (140) 8 = (96) 10 As 1 x 8 2 + 4 x 8 + 0x 1 = 64 + 32 = 96

What are types of firewalls, What are types of firewalls? There are con...

What are types of firewalls? There are conceptually two types of firewalls as: 1. Network Level 2. Application Level

Illustrate character coded data, Q. Illustrate Character Coded Data? Th...

Q. Illustrate Character Coded Data? The input output happens in the form of ASCII data. These ASCII characters are entered as a string of data. For illustration to get two numb

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