using INTERSECT and UNION in IN clause

Hi,

postgresql 7.0.2. Why by executing the following query

select * from magazine
where id in (     select mag_id from dict where word = 'akademie' intersect     select mag_id from dict where word =
'der'intersect     select mag_id from dict where word = 'klasse' )
 

I receive the following error:

ERROR: parse error at or near 'intersect'

while the query
     select mag_id from dict where word = 'akademie' intersect     select mag_id from dict where word = 'der' intersect
   select mag_id from dict where word = 'klasse' )
 

is executed successfully.

Is it possible to use INTERSECT and UNION keywords in subqueries?


Regards,
Alex