public boolean isHeteroClash(Tableaux labelF) {
		// TODO Auto-generated method stub
		// if there is a heterogeneous clash it returns true
		boolean clash;
		for(int ind=0;ind<ensConcepts.size();ind++){
			for(int j=0;j<labelF.getConceptsSize();j++){
				clash=ensConcepts.get(ind).isEqual(labelF.getConcept(j));
				if(clash)
					return true;
			}
		}
		return false;
	}