===== Lab 6: PowerLoom =====

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**.

==== PowerLoom ====

  * The main webpage of [[http://www.isi.edu/isd/LOOM/PowerLoom/|PowerLoom]];
  * You can download [[http://www.isi.edu/cgi-bin/LOOM/download-powerloom.cgi?ID=powerloom-3.2.0.zip|here]] the stable version;
  * PowerLoom documentation in [[http://www.isi.edu/isd/LOOM/PowerLoom/documentation/manual/manual.pdf|PDF]] or [[http://www.isi.edu/isd/LOOM/PowerLoom/documentation/manual/manual.html|HTML]] version.
  * Some **helpful** commands: <code>
(all-facts-of X) ;; prints out all known facts about X
(help assert)    ;; prints out help text about “assert”
(demo)           ;; leads you through various PowerLoom demonstrations
</code>

==== Doing Knowledge Representation and Reasoning with PowerLoom ====

  - **Basic Commands:**\\ Create a new, empty, module to work in and specify representation language syntax:\\ <code>
(defmodule "PL-USER/FAMILY")
(in-module "FAMILY")
(reset-features)
(in-dialect KIF)
</code> **Save** your module to disk (show up in your powerloom folder or the "kbs" subfolder), and **loading** it back later:\\ <code>
(save-module "FAMILY" "FAMILY.PLM")

(load "FAMILY.PLM")
(in-module "FAMILY")  ;; If not already in this module
</code>
  - **Defining a basic type/class predicate (a unary relation) called a "concept":**\\ <code>
(defconcept Person(?p))          ;; Defining a Person
(defconcept Male (?p Person))    ;; A Male is a Person
(defconcept Female (?p Person))  ;; A Female is a Person
</code>
  - **Basic TELLing and ASKing:**\\ <code>
(assert (Male John))
(assert (Female Mary))

(ask (Male John))
(ask (Female Mary))
</code>
  - **Adding First Order Logic (FOL) axioms:**\\ Being a **Male** implies you are a person: <code>
(assert (forall (?x) (=> (Male ?x) (Person ?x))))
</code> Do the same for **Females**.
  - **Asking for possible substitutions:**\\ Returns **one** possible substitutions for ?p if it exists:<code>
(retrieve (Person ?p))
</code> Returns **all** possible substitutions for ?p: <code>
(retrieve all (Person ?p))
</code>
  - **The Open-World semantics:**\\ The following should be unknown since it wouldn't conflict with the KB <code>
(ask (Male Mary))
</code> If we add this assertion, being a male implies you are not a female: <code>
(assert (forall (?p) (<=> (Male ?p) (not (Female ?p)))))
</code> Create the same assertion for **Females**.
  - **Defining a regular relation predicate:**\\ The following creates a new **Predicate** called **BrotherOf**:<code>
(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
</code> Create a new predicate called **ParentOf**.
  - **Defining a regular function and using it:**\\ If a (binary) relation always maps its first argument to exactly one value (i.e., if it it “single-valued”) we can specify it as a function instead of a relation. <code>
(deffunction GetFather ((?p1 Person)) :-> (?p2 Male))   ;; The second value (after the symbol ":->") is the output variable of the function
</code>We can refer to a function in a sentence in this way: <code>
(assert (= (GetFather Mary) Zod))
</code> A new **axiom** that uses a function and equivalence <code>
(assert (<=> (= (GetFather ?c) ?f) (and (Male ?f) (ParentOf ?f ?c))))
</code> Ask the following:
     * Is Zod Male?
     * Is Zod Mary's parent?
  - **Defining more family Relations:**\\ Now you are on your own...add more **family relations** like:
    * SisterOf;
    * AreSiblings;
    * SonOf, DaughterOf, ChildOf;
    * GrandmotherOf and GrandfatherOf;
    * UncleOf, AuntOf;
    * ... \\ and try **answering** questions like:
    * Is X a sibling of Y?
    * Who are X's grandmothers?
    * Who are X's uncles?
    * Does X's mother's mother have a male child?
    * ...