Cascaded Queries

The output of one query:

nick	mbox
Bob	<bob@work.example>
Sue	<roberto@home.example>
Amy	<amy@foo.example>

can provide constraints for another:

PREFIX irc:   <http://irc.example/ns#> 
SELECT ?cohort
WHERE
  ( ?msg irc:from ?nick )
  ( ?msg irc:to ?cohort )