Using overlaps()

Greetings.

The Postgres Book implies that there is a function overlaps() that takes
two pairs of dates and returns true if they overlap.  However, I get an
error trying to use it:

demogdata=> select event_id from event_detail where overlaps
(date_effective, date_expires, '1-mar-2000'::datetime , now()::datetime);
ERROR:  No such function 'overlaps' with the specified attributes
demogdata=> select event_id from event_detail where (date_effective,
date_expires) overlaps ('1-mar-2000'::date , now()::date);
ERROR:  parser: parse error at or near "overlaps"

Any advice?

Thanks.

---------------------------------------------------------------------
Andrew J. Perrin - aperrin@demog.berkeley.edu - NT/Unix Admin/Support
Department of Demography    -    University of California at Berkeley
2232 Piedmont Avenue #2120  -    Berkeley, California, 94720-2120 USA
http://demog.berkeley.edu/~aperrin --------------------------SEIU1199