_:b1 <http://example.org/base#a> <http://example.org/base#b> .
<http://example.org/base#c> <http://example.org/base#d> _:b2 .
_:b3 <http://example.org/base#a> <http://example.org/base#b> <http://example/graph> .
<http://example.org/base#c> <http://example.org/base#d> _:b4 <http://example/graph> .