org.deri.iris.rules.stratification
Class GlobalStratifier

java.lang.Object
  org.deri.iris.rules.stratification.GlobalStratifier

All Implemented Interfaces:

IRuleStratifier

public class GlobalStratifier
extends Object
implements IRuleStratifier

The global stratification algorithm. This algorithm does not modify/create/delete any rules.

See Also:

org.deri.iris.rules.IRuleStratifier#stratify()

Constructor Summary

GlobalStratifier()

Method Summary

static boolean	checkRuleHeadEquality(IRule rule, int stratum) Checks if a rule with head equality is stratified.
List<List<IRule>>	stratify(List<IRule> rules) Stratify the rules, i.e.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GlobalStratifier

public GlobalStratifier()

Method Detail

stratify

public List<List<IRule>> stratify(List<IRule> rules)

Description copied from interface: IRuleStratifier

Stratify the rules, i.e. arrange them in to groups such that each increasing level of rules can be evaluated before the next higher level of dependent rules.

Specified by:

stratify in interface IRuleStratifier

Parameters:

rules - The collection of rules to stratify

Returns:

The rules arranged in to strata. The number of rules returned may be different to the number provided, because the stratification technique might require the rules to be re-written.

checkRuleHeadEquality

public static boolean checkRuleHeadEquality(IRule rule,
                                            int stratum)

Checks if a rule with head equality is stratified. A program is stratified if and only if rules with head equality are in the bottom stratum and they don't have negated predicates.

Parameters:

rule - The rule to check if stratified.

stratum - The stratum of the rule.

Returns:

true if the rule is stratified, false otherwise.