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

Multiple instruction and multiple data stream (mimd), Multiple Instruction ...

Multiple Instruction and Multiple Data stream (MIMD) In this association, multiple control units and multiple processing elements are prepared as in MISD. But the discrepancy i

Define bootstrap loader, Define bootstrap loader? The ROM portion of ma...

Define bootstrap loader? The ROM portion of main memory is required for storing an initial program known as bootstrap loader. It is a program whose function is to start the com

Learning weights in perceptrons, Learning Weights in Perceptrons: Furt...

Learning Weights in Perceptrons: Furthermore details are we will look at the learning method for weights in multi-layer networks next lecture. Thus the following description o

What are attributes, What are Attributes?  Attributes are declarative ...

What are Attributes?  Attributes are declarative tags in code that insert additional metadata into an assembly. There exist two types of attributes in the .NET Framework: Pred

Explain sequential sharing, Explain Sequential sharing. Sequential s...

Explain Sequential sharing. Sequential sharing: In this technique of sharing, a file can be shared through only one program at a time, it is file accesses by P1 and P2 are

#logic function, Minimize the following logic function using K-maps and rea...

Minimize the following logic function using K-maps and realize using NAND and NOR gates. F(A,B,C,D) =?_m(1,3,5,8,9,11,15) + d(2,13).

Translation look aside buffer - computer architecture, Translation Look asi...

Translation Look aside Buffer :    A TLB is a cache that holds only page table mapping If there is no matching entry in the TLB for a page ,the page table have to

Explain high performance of instruction execution, Q. Explain High performa...

Q. Explain High performance of Instruction execution? High performance of Instruction execution: While mapping of HLL to machine instruction the compiler favours relatively sim

By which the speech of side tone is heard, Side tone is the speech heard by...

Side tone is the speech heard by (A)  the receiving subscriber (B)  both the receiving and calling subscriber (C) by on looker (D) by calling subscriber Ans

What is external procedures, Q. What is External Procedures? These proc...

Q. What is External Procedures? These procedures are written as well as assembled in separate assembly modules and afterwards linked together with the main program to form a bi

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