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

Determine the input and output devices, I/O devices need to be matched up t...

I/O devices need to be matched up to computer application. -  Computer-aided design (graph plotters, large screens, etc.) -  Virtual reality (data gloves, data goggles, etc.)

What is test requirements, Test requirements are definite in the Requiremen...

Test requirements are definite in the Requirement Hierarchy in TestManager. The requirements hierarchy is a graphical outline of requirements and nested child requirements. Req

COA, During instruction execution, there are other parts of the CPU that ca...

During instruction execution, there are other parts of the CPU that can determine when a physical register might be freed. Briefly describe where else we can put freeing logic and

Explain salient points about indirect addressing, Q. Explain salient points...

Q. Explain salient points about indirect addressing? A number of salient points about this scheme are:  In this addressing scheme effective address EA and contents of th

Computer peripherals, Describe the 8251 A programmable communication interf...

Describe the 8251 A programmable communication interface

Performance analysis, In order to calculate the performance of the program,...

In order to calculate the performance of the program, the normal form of analysis of the program is to simply measure the total amount of CPU time needed to implement the various p

Shared-memory programming model, Q. Shared-memory programming model? In...

Q. Shared-memory programming model? In shared-memory programming model tasks share a common address space that they read and write asynchronously. Several mechanisms like semap

Define internet infrastructure, As we know how packets travel from one comp...

As we know how packets travel from one computer to another over the Internet. However what's in-between? Actually what makes up the Internet infrastructure or backbone? Fi

Draw the logic diagram of 4-bit odd parity checkers, Normal 0 f...

Normal 0 false false false EN-IN X-NONE X-NONE

Determine the process of kernel, What are the events done by the Kernel aft...

What are the events done by the Kernel after a process is being swapped out from the main memory? When Kernel changes the process out of the primary memory, it performs the fol

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