4 Ask and Tell

The general interaction with AILog is to tell it clauses and to ask it queries (which are bodies). It replies with answers, which are instances of the query that are consequences of its knowledge base. The user can then either explore how the system derived an answer or why the system didn't find another answer.

To add a clause to the knowledge base you issue the command:

ailog: tell clause.

ailog: tell parent(X,Y) <- mother(X,Y).
ailog: tell parent(X,Y) <- father(X,Y).
ailog: tell grandfather(X,Y) <- father(X,Z) & parent(Z,Y).
ailog: tell grandmother(X,Y) <- mother(X,Z) & parent(Z,Y).
ailog: tell father(randy,sally).
ailog: tell father(randy,joe).
ailog: tell mother(sally,mary).
ailog: tell father(joe,sue).

You can ask a query to determine if some body is a consequence of the knowledge base:

ailog: ask query.

where query is a body. The system will respond with either an instance of the query that is a consequence of the knowledge base or "No. query doesn't follow from the knowledge base" if there are no answers. When the system have given an answer you can reply with:

ok.

to indicate that you don't want any more answers

more.

to ask for more answers

how.

to investigate how that answer was produced (see Section 6.1)

help.

to get a menu of available answers (this option is available at all points where the system is asking for a response)

If you reply with more, the system either finds another answer or reports there are no more answers.

ailog: ask grandfather(randy,mary).
Answer: grandfather(randy,mary).
  [ok,more,how,help]: ok.

ailog: ask grandfather(joe,mary).
No. grandfather(joe,mary) doesn't follow from the knowledge base.

ailog: ask grandfather(G,C).
Answer: grandfather(randy,mary).
  [ok,more,how,help]: more.
Answer: grandfather(randy,sue).
  [ok,more,how,help]: more.
No more answers.