@prefix rr: <http://www.w3.org/ns/r2rml#> .
@prefix ex: <http://example.com/ns#> .
@prefix rrf: <http://kdeg.scss.tcd.ie/ns/rrf#>
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
    
<#BooksTriplesMap>
    rr:logicalTable [ rr:tableName "COLAUTHOR" ];

    rr:subjectMap [
        rr:template "http://example.com/book/{BOOKID}";
    ];
    
    rr:predicateObjectMap [
        rr:predicate ex:writtenby;
        rr:objectMap [ 
		  rrf:gatherAsNonEmpty (
        		[ rr:column "TITLE" ]
        	) ;
          rrf:collectAs rdf:List ;
        ];
    ];
    
    .