[pm#graph1_on_conference
     [any #conference (^$(no inheritance)$^),
          pm#topic: a #thing,
          pm#place: an #address,
          pm#from_time: a pm#time_measure,
          pm#until_time: a pm#time_measure,
          may have for pm#object: a pm#conference_proceedings,
          pm#title: a pm#string,
          pm#organizer: a #person,
          pm#participant: a #person,
          may have for pm#relation_from_situation (^$(explore)$^): a pm#thing,
          may have for pm#url: a pm#URL]
];