public Map<String, Integer> getTermCounts() {
		if (termCounts == null) {
			Counter count = new Counter();
			for (Sentence sentence : this.sentences) {
				for (String term : sentence.terms) 
				{
					count.add(term);
				}
			}
			termCounts = count.toHashMap();
		}
		return termCounts;
	}