_:vb50911273	<http://www.w3.org/ns/r2rml#column>	"last_name" .
_:vb50911271	<http://www.w3.org/ns/r2rml#constant>	<http://xmlns.com/foaf/0.1/lastName> .
_:vb50911272	<http://www.w3.org/ns/r2rml#objectMap>	_:vb50911273 .
_:vb50911272	<http://www.w3.org/ns/r2rml#predicateMap>	_:vb50911271 .