n(P(edge-element-presence-none,=,root:http://www.sleepycat.com/2002/dbxml.authors),V(node-element-substring-string,biography,=,'hoc'),V(node-element-substring-string,biography,=,'ock'),V(node-element-substring-string,biography,=,'cke'),V(node-element-substring-string,biography,=,'key')) P(edge-attribute-equality-string,prefix,author.@id)