in this tutorial:
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .
@prefix owl: <http://www.w3.org/2002/07/owl#> .
and also
@prefix : <#> .
eg
:pat :child [ :age "4" ] , [ :age "3" ].
