Relation pm#cause (pm#situation,pm#situation)  see also rst#cause
  supertype:  pm#before_situation  pm#why_relation
  inverse:  pm#consequence
  similar_to:  lis#cause_of_event
  subtype:  sumo#causes (sumo#process,sumo#process)  the process in the 1st argument brings about the process in the 2nd argument