public R1Interval intersection(R1Interval y){
  return new R1Interval(Math.max(lo(),y.lo()),Math.min(hi(),y.hi()));
}

public R1Interval intersection ( R1Interval y ) { return new R1Interval ( Math . max ( lo ( ) , y . lo ( ) ) , Math . min ( hi ( ) , y . hi ( ) ) ) ; }
return the intersection of this interval with the given interval . empty intervals do not need to be special - cased .
