  We present a novel technique to identify calendar-based (annual, monthly and
daily) periodicities of an interval-based temporal pattern. An interval-based
temporal pattern is a pattern that occurs across a time-interval, then
disappears for some time, again recurs across another time-interval and so on
and so forth. Given the sequence of time-intervals in which an interval-based
temporal pattern has occurred, we propose a method for identifying the extent
to which the pattern is periodic with respect to a calendar cycle. In
comparison to previous work, our method is asymptotically faster. We also show
an interesting relationship between periodicities across different levels of
any hierarchical timestamp (year/month/day, hour/minute/second etc.).
