PREFIX :       <http://example/>

:s :p1 :o .
<<:s :p1 :o>> :q :z .

# pattern-3
:a1 :b <<:s :p1 :o>>  .
<<:s :p1 :o>> :b :a2 .

# pattern-5
:s :p2 :o .
<<:s :p2 :o>> :sym <<:s :p2 :o>> .

# pattern-6
<<:s :p2 :o>> :p3 :z .
<< <<:s :p2 :o>> :p3 :z >> :q :o .