Solution

Solution

1. Give the intended interpretation of each symbol used. We assume that the denotation of the constants (i.e., phi) is given as above, and that we use doc1, doc2, etc for particular documents. We assume the following meaning for the predicate symbols:
   • computer_selects(Comp,Room) is true if computer Comp has selected room Room to print on.
   • plugged_into(Printer,Room) is true if Printer is plugged into the printer port of Room.
   • printed_from(Doc,Comp) is true if document DOc is printed from computer Comp.
   • printed_in_room(Doc,Room) is true if the document Doc has been printed in Room.
   • on_printer(Doc,Pr) is true if document Doc has been printed on printer Pr.
2. Give the general axioms that are true for all configurations of printers.

   printed_in_room(Doc,Room) <-
      printed_from(Doc,Comp) & 
      computer_selects(Comp,Room).
   
   on_printer(Doc,Pr) <-
      printed_in_room(Doc,Room) &
      plugged_into(Pr,Room).
   

3. Show that your axiomatization works for more than one configuration.

   Here is one (sensible) configuration:

   computer_selects(c1,r101).
   computer_selects(c2,r202).
   computer_selects(c3,r202).
   plugged_into(pr1,r101).
   plugged_into(pr2,r202).
   printed_from(doc1,c1).
   printed_from(doc2,c2).
   printed_from(doc3,c3).
   

   Here is one (not so sensible) configuration:

   computer_selects(c1,r101).
   computer_selects(c2,r202).
   computer_selects(c3,r202).
   plugged_into(pr1,r101).
   plugged_into(pr2,r101).
   printed_from(doc1,c1).
   printed_from(doc2,c2).
   printed_from(doc3,c3).
   

   To think about: Where does doc1 get printed? Where does doc2 get printed (in what room and on what printer)?

Solution