[graph1_on_housing
     [any housing (^$(no inheritance)$^),
          address: an address,
          may have for phone_No: a string,
          may have for fax_No: a string,
          may have for owner: a person_or_organization (^$(explore 1)$^),
          may have for facility: a facility (^$(explore 2)$^),
          may have for part: a room,
          may be object of: a commercial_transaction (^$(explore 1)$^),
          monetary_value: a monetary_value,
          may be doer/object/result/place of (^$(explore)$^): a situation]
];