D(node-metadata-equality-string,name:http://www.sleepycat.com/2002/dbxml,=,'users.xml',P(edge-element-equality-string,prefix,user_tuple.userid)) D(node-metadata-equality-string,name:http://www.sleepycat.com/2002/dbxml,=,'items.xml',P(edge-element-equality-string,prefix,item_tuple.itemno)) D(node-metadata-equality-string,name:http://www.sleepycat.com/2002/dbxml,=,'bids.xml',n(V(edge-element-equality-string,bid_tuple.itemno,=,'[to be calculated]'),V(edge-element-equality-string,bid_tuple.userid,=,'[to be calculated]'))) V(edge-element-equality-string,item_tuple.itemno,=,'[to be calculated]') P(edge-element-equality-string,prefix,bid_tuple.itemno) V(edge-element-equality-string,user_tuple.userid,=,'[to be calculated]') P(edge-element-equality-string,prefix,bid_tuple.userid)