Predicate argument structures are annotated as attributes, "mod" and "argX," which point to the IDs of the argument phrases.
our motivation for employing semantic retrieval  [sentence] >> ([word arg1="$subject" arg2="$object" rel_type="activation"] & ([phrase id="$subject"] > [entity_name type="gene" gene_id="GHS019685"]) & ([phrase cat="np" id="$object"] > [entity_name type="gene" gene_id="GHS009426"])) Figure 7: Queries of the extended region algebra for Query 4-3 (upper: keyword search, lower: semantic search) was to provide a device for the accurate identification of relational concepts.