Research On New Compress Method On Table Constraint Based On STR Algorithm

One of the key ways of constrained programming is the constraint propagation,it used for solving constraint satisfaction problems,also can deal with industrial modeling issues,such like design and configuration,databases,and preferences modeling.In most cases,table constraints provide a unique practical approach to express his constraint requirements for non expert users.Therefore,the focus of the study is on how to make the table constraint algorithms maintain GAC much more fast.The study of GAC algorithms on the table constraint can be traced back to GAC4 and GAC-Schema,the classical algorithm through different methods to iterate the current tuple.A recent study based on the AC5 algorithm,have a very good efficiency in small scale constraint table algorithm.For the large constraint table,in order to maintain the dynamic support so the efficiency of the algorithm is not very obvious.Because of the size of the table with variable constraints might growth increases exponentially,so in recent years,the research on how to reduce the constraint table space has been like a raging fire,in some constraint propagation algorithms frequently usable compression method,to reduce the space consumption restriction and improve the operation speed of the GAC algorithm.The Tries,MDDs,DFA are the general structural constraints of the table to compact representation,the aim is to promote the filtering process.In recent years,table compression methods are frequently used in some constraint propagation algorithms to cut down the consumption of constraint table space,and at the same time increase running speed of the GAC algorithm.For the past few years,short support method is the most frequently used table compression methodin constraint propagation algorithms.This method can propagate more constraints than original STR algorithms especially when the memory is small.But when the compression ratio is low,short support method improves the running speed effect is not obvious.In this paper,we present a new method to compress constraint table,called STRO,combined short support compression method and bit-wise operation.The method STRO improves the running speed of STR algorithm,and at the same time,the compression of space effect is better.Experimental results show that besides the table under the condition of the average size is not particularly small,STRO is faster and more efficient than ShortSTR2 and STR2 algorithm;When compared with algorithm STRbit,the compression rate of algorithm STRO is bigger,it can save more space and replace STRbit on time.