Center for Analysis and Design of Intelligent Agents

In this lab we will work with First Order Logic and PowerLoom, a knowledge representation system. You will have to go through the following steps and create some logical statements representing Family Relations.

• The main webpage of PowerLoom;
• You can download here the stable version;
• PowerLoom documentation in PDF or HTML version.

1. Basic Commands:
   Create a new, empty, module to work in and specify representation language syntax:
   

   (defmodule "PL-USER/FAMILY")
   (in-module "FAMILY")
   (reset-features)
   (in-dialect KIF)

   Save your module to disk (show up in your powerloom folder or the “kbs” subfolder), and loading it back later:
   

   (save-module "FAMILY" "FAMILY.PLM")
   
   (load "FAMILY.PLM")
   (in-module "FAMILY")  ;; If not already in this module

2. Defining a basic type/class predicate (a unary relation) called a “concept”:
   

   (defconcept Person(?p))         ;; Defining a Person
   (defconcept Male (?p Person))   ;; A Male is a (subset of) Person
   (defconcept Female (?p Person)) ;; A Female is a (subset of) Person

3. Basic TELLing and ASKing:
   

   (assert (Male John))
   (assert (Female Mary))
   
   (ask (Male John))
   (ask (Female Mary))

4. Adding First Order Logic (FOL) axioms:
   Being a Male implies you are a person:

   (assert (forall (?x) (=> (Male ?x) (Person ?x))))

   Do the same for Females.

5. Asking for possible substitutions:
   Returns one possible substitutions for ?p if it exists:

   (retrieve (Person ?p))

   Returns all possible substitutions for ?p:

   (retrieve all (Person ?p))

6. The Open-World semantics:
   The following should be unknown since it wouldn't conflict with the KB

   (ask (Male Mary))

   If we add this assertion, being a male implies you are not a female:

   (assert (forall (?p) (<=> (Male ?p) (not (Female ?p)))))

   Create the same assertion for Females.

7. Defining a regular relation predicate:
   The following creates a new Predicate called BrotherOf:

   (defrelation BrotherOf ((?p1 Male) (?p2 Person)))
   (assert (BrotherOf John Mary))
   (assert (Person Olaf))
   (assert (BrotherOf Olaf Mary))
   
   (retrieve all (BrotherOf ?x Mary))    ;; Retrieve all Brothers of Mary

   Create a new predicate called ParentOf.

8. Defining a regular function and using it:
   

   (deffunction GetFather ((?p1 Person)) :-> (?p2 Male))   ;; The first value is the 
   
   (assert (= (GetFather Mary) Zod))

   A new axiom that uses a function and equivalence

9. Defining a basic type/class predicate (a unary relation) called a “concept”: