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    • de.invation.code.toval.math.logic.Clause Maven / Gradle / Ivy

    package de.invation.code.toval.math.logic;


import java.util.Comparator;
import java.util.Iterator;

import de.invation.code.toval.types.HashList;



public class Clause extends HashList implements Comparator{
	
	private static final long serialVersionUID = 1L;
	
	public Clause(){}
	
	public Clause(Literal l){
		add(l);
	}
	
	public Literal getFirst(){
		if(!isEmpty()){
			return super.get(0);
		} else {
			return null;
		}
	}
	
	public HashList getItems(){
		HashList set = new HashList();
		for(Iterator iter=iterator(); iter.hasNext();)
			set.add(iter.next().getItem());
		return set;
	}
	
	public Clause union(Clause k){
		Clause nk = new Clause();
		nk.addAll(k);
		nk.addAll(this);
		return nk;
	}
	
	public boolean containsItem(Object item){
		for(Iterator iter=iterator(); iter.hasNext();)
			if(item.equals(iter.next().getItem()))
				return true;
		return false;
	}
	
	/**
	 * Tries to accomplish a resolution along the variable item.
	 * @param clause
	 * @param item
	 */
	public ResolveResult resolve(Clause clause, Object item){
		Literal lPos = new Literal(item, true);
		Literal lNeg = new Literal(item, false);
		if( (contains(lPos) && clause.contains(lNeg)) || (contains(lNeg) && clause.contains(lPos)) ){
			Clause resolvent = union(clause);
			resolvent.remove(lPos);
			resolvent.remove(lNeg);
			return new ResolveResult(resolvent, item);
		}
		return null;
	}
	
	public boolean hasTwinLiterals(){
		for(int i=0; i i = iterator(); i.hasNext();){
				s += i.next().toString();
				if(i.hasNext()){
					s += ",";
				}
			}
			s += "}";
			return s;
		}
	}


}
    
    
    
    

    




    
    
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