code: private void addPairs() {
  		GvmCluster<S,K> cj = clusters[count];
  		int c = count - 1; //index at which new pairs registered for existing clusters
  		for (int i = 0; i < count; i++) {
  			GvmCluster<S,K> ci = clusters[i];
  			GvmClusterPair<S,K> pair = new GvmClusterPair<S,K>(ci, cj);
  			ci.pairs[c] = pair;
  			cj.pairs[i] = pair;
  			pairs.add(pair);
  		}
  		
  	}
docs: assumes pairs are contiguous