net.sf.tweety.arg.aspic.syntax.InferenceRule Maven / Gradle / Ivy
/*
* This file is part of "Tweety", a collection of Java libraries for
* logical aspects of artificial intelligence and knowledge representation.
*
* Tweety is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 3 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see .
*
* Copyright 2016 The Tweety Project Team
*/
package net.sf.tweety.arg.aspic.syntax;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import net.sf.tweety.commons.Signature;
import net.sf.tweety.commons.util.rules.Rule;
import net.sf.tweety.logics.commons.syntax.interfaces.Invertable;
/**
* @author Nils Geilen
*
* This stands for an inference rule or for a premise if premises has length 0.
* If this is a premise and defeasible it is an ordinary premise else it is an axiom.
*
* @param is the type of the language that the ASPIC theory's rules range over
*/
public abstract class InferenceRule implements Rule {
/**
* The rule's conclusion
*/
private T conclusion;
/**
* The rule's premises
*/
private Collection premises = new ArrayList<>();
/**
* Identifying name. used e.g. for formula generation
*/
private String name;
/**
* Creates an empty instance
*/
public InferenceRule(){
}
/**
* Constructs a new inference rule of rule p -> c if strict or p => c else
* @param conclusion ^= p
* @param premise ^= c
*/
public InferenceRule(T conclusion, Collection premise) {
this.conclusion = conclusion;
this.premises = premise;
}
/**
* @return true iff this rule is defeasible
*/
public abstract boolean isDefeasible();
/* (non-Javadoc)
* @see net.sf.tweety.arg.aspic.syntax.AspicWord#toString()
*/
@Override
public String toString() {
StringWriter sw = new StringWriter();
sw.write("(");
if(getName()!=null)
sw.write(getName()+": ");
Iterator i = premises.iterator();
if(i.hasNext())
sw.write(i.next().toString());
while(i.hasNext())
sw.write(", "+i.next());
if(isDefeasible())
sw.write(" => ");
else
sw.write(" -> ");
sw.write(conclusion+"");
sw.write(")");
return sw.toString();
}
/**
* @return a strict instance of this rule
*/
public StrictInferenceRule toStrict() {
StrictInferenceRule result = new StrictInferenceRule<>(conclusion, premises);
result.setName(name);
return result;
}
/**
* @return a defeasible instance of this rule
*/
public DefeasibleInferenceRule toDefeasible() {
DefeasibleInferenceRule result = new DefeasibleInferenceRule<>(conclusion, premises);
result.setName(name);
return result;
}
/**
* Returns the name if it has one, else it returns the hashcode
* @return an identifier for this rule
*/
public String getIdentifier() {
if (getName() == null)
return ""+hashCode();
else
return getName();
}
/**
* Returns the name
* @return this rul's name
*/
public String getName() {
return name;
}
/**
* Sets the name
* @param name new name
*/
public void setName(String name) {
this.name = name;
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#isFact()
*/
@Override
public boolean isFact() {
return premises.isEmpty() && conclusion != null;
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#isConstraint()
*/
@Override
public boolean isConstraint() {
return false;
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#setConclusion(net.sf.tweety.commons.Formula)
*/
@Override
public void setConclusion(T conclusion) {
this.conclusion = conclusion;
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#addPremise(net.sf.tweety.commons.Formula)
*/
@Override
public void addPremise(T premise) {
this.premises.add(premise);
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#addPremises(java.util.Collection)
*/
@Override
public void addPremises(Collection premises) {
this.premises.addAll(premises);
}
/* (non-Javadoc)
* @see net.sf.tweety.arg.aspic.syntax.AspicWord#getSignature()
*/
@Override
public Signature getSignature() {
Signature sig = conclusion.getSignature();
for (T w: premises)
sig.addSignature(w.getSignature());
return sig;
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#getPremise()
*/
@Override
public Collection getPremise() {
return premises;
}
/* (non-Javadoc)
* @see net.sf.tweety.commons.util.rules.Rule#getConclusion()
*/
@Override
public T getConclusion() {
return conclusion;
}
}