Making Queries

• We interact with a logic program by making queries
• A query is a conjunction of atoms
  (which we want to be prove)
• An answer will consist of bindings for the variables in the query which make it true w.r.t. the program
• Several (different) answers are possible
• We will mark a query starting with ?-
• Example:

  ?- sound(spot, X).
  X = bark

  ?- sound(A, roar).
  A = hobbes

  ?- animal(barry).
  yes

  ?- animal(X).
  X = spot ;
  X = barry ;
  X = hobbes

  ?- sound(A, S).