code: public static boolean overlaps(TermOccurrence o1, TermOccurrence o2) {
  		return o1.getSourceDocument().equals(o2.getSourceDocument()) 
  				  && o1.getBegin() < o2.getEnd()
  				  && o2.getBegin()< o1.getEnd();
  	}
docs: True if both source documents are the same and if the
  offsets in the document overlaps.
  
  The overlap is interpreted in the sense of opening intervals. I.e
  if the begin of the second interval is the end of the first interval, this
  is not an overlap.
  
  @param o1
  @param o2
  @return