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