Relation nsm#after (?,?)
  supertype:  pm#binary_relation (pm)  in WebKB, most relation types are binary and some have a variable number of arguments (as in KIF), hence this type is currently only specialized by types that I do not want to see as direct subtypes of pm#relation
  subtype:  pm#after (pm#time_measure,pm#time_measure)
  subtype:  pm#until_time__untiltime__to_time (pm#situation -> pm#time_measure)
     subtype:  pm#arrival_time__arrivaltime (pm#process -> pm#time_measure)
  subtype:  pm#before_situation (pm#situation,pm#situation)  in WebKB, do not use these relations, use their inverses
     subtype:  pm#previous_situation (pm#situation -> pm#situation)
     subtype:  pm#beginning_situation__beginningsituation (pm#situation -> pm#situation)
     subtype:  pm#precondition (pm#process,pm#situation)
     subtype:  pm#cause (pm#situation,pm#situation)  see also rst#cause
        subtype:  sumo#causes (sumo#process,sumo#process)  the process in the 1st argument brings about the process in the 2nd argument