Name the common institute of Robert hall and Erica Frank ?
SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Robert_Hall_(economist)> <http://dbpedia.org/ontology/institution> ?uri. <http://dbpedia.org/resource/Erica_Frank> <http://dbpedia.org/ontology/institution> ?uri . }
Robert_Hall_(economist) Erica_Frank