Relation pm#part_in_Dolce_Lite (dl#entity,dl#entity)
  supertype:  pm#part
  subtype:  dl#part (dl#entity,dl#entity)  the subpart may or may not be different from the whole
     subtype:  dl#component (dl#entity,dl#entity)
     subtype:  dl#atomic_part (dl#entity,dl#atom)  an undivisible part
        subtype:  dl#temporary_atomic_part__AtP (dl#entity,dl#atom)
  subtype:  dl#proper_part (dl#entity,dl#entity)  the subpart is different from the whole
  subtype:  dl#temporary_proper_part (dl#endurant,dl#endurant)
  subtype:  dl#temporary_part__temporarypart (dl#endurant,dl#endurant)
     subtype:  dl#temporary_component__temporarycomponent (dl#endurant,dl#endurant)
  subtype:  dl#constant_part (dl#entity,dl#entity)
  subtype:  dl#sibling_part__siblingpart (dl#entity,dl#entity)