Relation dc#Relation (?,?)  to specify a reference to a related resource; in WebKB, pm#relation or MORE PRECISE RELATION TYPES SHOULD BE USED INSTEAD
  supertype:  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:  refers (?,?)  the 1st argument mentions or includes a reference to the 2nd argument, e.g., an article whose topic is a recent change in the price of oil may refer to many other things, e.g., the general state of the economy, the weather in California, the prospect of global warming, the options for alternative energy sources, the stock prices of various oil companies, etc.
     subtype:  names__name (string,?)  the string names the 2nd argument
        subtype:  unique_identifier (string,?)  the string uniquely identifies the 2nd argument
     subtype:  represents (?,?)  the 1st argument in some way indicates, expresses, connotes, pictures, describes ... the 2nd argument
        subtype:  contains_information (content_bearing_object,proposition)  relates a content_bearing_object to the proposition it expresses; examples include the relationships between a physical novel and its story and between a printed score and its musical content
        subtype:  realization (?,?)
     subtype:  see_also__seealso (?,entity)
        subtype:  is_defined_by (?,entity)  in WebKB, pm#definition SHOULD BE USED INSTEAD
           subtype:  definition (?,description_content/medium/container)  see also #definition
              subtype:  definition (description_content/medium/container,description_content/medium/container)  a logical relation should be used instead of this relation
        subtype:  imports__import (?,entity)  if imports(X,Y) and you believe X, then you should believe what is in Y