--- pl:dydaktyka:dss:rules:intro [2017/11/28 13:33]
msl
+++ pl:dydaktyka:dss:rules:intro [2019/06/27 15:50] (aktualna)
@@ Linia 2: / Linia 2: @@
 ===== Download =====
-Please download the following files containg simple knowledge bases about a family:
+Please download the following files containing simple knowledge bases about a family:
-  * CLIPS file:
+  * CLIPS file: {{ :pl:dydaktyka:dss:rules:family_en.clp.zip |}}
-  * Prolog file:
+  * Prolog file: {{ :pl:dydaktyka:dss:rules:family_en.pl |}}
-  * Manual for CLIPS: {{: en: didactics: rules: lab: labs: bpg.pdf | Basic Programming Guide}} [[http://clipsrules.sourceforge.net/documentation/v630/bpg.htm|version online]]
+  * Manual for CLIPS: {{:pl:dydaktyka:rules:lab:labs:bpg.pdf|Basic Programming Guide}}, [[http://clipsrules.sourceforge.net/OnlineDocs.html|version online]]
 ===== Knowledge Bases =====
@@ Linia 18: / Linia 18: @@
 Defining deffacts: initial-facts
 Defining defrule: child +j
-TRUE </ code> The ** TRUE ** is the most important part of this feedback. If ** FALSE ** appears, it means that loading failed.
+TRUE </code> The ** TRUE ** is the most important part of this feedback. If ** FALSE ** appears, it means that loading failed.
   * Prolog: <code> [family]. </code> The succesful loading should display something similar to: <code>
 % family compiled 0.01 sec, 9,232 bytes
@@ Linia 49: / Linia 49: @@
   * What are the names of all the fathers: <code> father(Father, _). </code>
   * What sons does Dariusz have: <code> father(dariusz, Son), man(Son). </code>
+===== 4. How to use Rules =====
+Both files contain a rule defines who/what is a ** child**.
+  * How to interpret these rules?
+  * Do they use the same notion of a **child**?
+CLIPS failed to start this rule (previous point). In Prolog, we can query using this rule: <code>child(X, Y).</code>
+  * Run the above query and ...
+  * describe what happened?
+  * Has the situation been analogous to that in CLIPS?
+  * Does the rule in CLIPS failed because of the same reason?
+===== 5. Creating Rules =====
+In order to run the **child** rule, we have to define:
+  * In CLIPS: a rule that adds a parent to the knowledge base (changing the knowledge base will trigger the next inference cycle): <code>
+(defrule parent
+ (or (mother ?x ?y) (father ?x ?y))
+=>
+ (assert (parent ?x ?y))
+)</code>
+  * In Prolog: a rule defining a relationship (child, parent): <code>
+parent(X, Y) :-
+  father(X, Y).
+parent(X, Y) :-
+  mother(X, Y). </code> It is worth noting that in the case of Prolog, we define two rules. One can assume that there is a conjuction (**OR**) between these two rules.
+  * Repeat steps:
+    * CLIPS: 1. and 3. (start with executing ''(clear)'' to clear the fact base)
+    * Prolog: 1 and 4.
+  * How many facts are there in the CLIPS database?
+  * What are the active rules in CLIPS?
+  * Why is the **child** rule inactive?
+==== 5.1. Adding Knowledge to the KB ====
+=== 5.1.1. Son and daughter ===
+We can try now to supplement the current KB with new rules, that define other relationships:
+  * Both tools can answer who is the child of which parent. How to extend the rules base of both tools with the help of the **child** concept so that they can tell who is the son and who is the daughter?
+    * Define the appropriate rules.
+    * Start the inference to check if the defined rule is correct.
+    * You can also try to simply display the facts in CLIPS.
+=== 5.1.2. Marriage ===
+  * The knowledge base can also be supplemented by a rule defining **marriage**. With existing facts and rules, you can define that two people are married if:
+    * are different sex,
+    * have a common child.
+  * This rule will cause the inference to omit the childless couples. In order to define the proper notion of **marriage**, KB would have to be supplemented with additional facts (what facts?)
+=== 5.1.3. Other ===
+Knowing that the concepts **brother** is defined as follow:
+  * CLIPS: <code>
+(defrule brother
+ (siblings ?x ?y)
+ (man ?x)
+=>
+ (assert (brother ?x ?y))
+)</code>
+  * Prolog: <code>
+brother(X, Y) :-
+  siblings(X, Y),
+  man(X).</code>
+Define the following rules:
+  * siblings(X,Y) --- two different people with a common parent;
+    * tip: ** (test (neq ?x ?y)) ** checks inequality of variables.
+    * question: why do you have to use ** test ** keyword?
+  * sister(X,Y)
+  * grandfather(X,Y)
+  * grandmother(X,Y)
+  * grandparent(X,Y) --- tip: use ** OR **
+  * cousins(X,Y) --- two different people with a common grandparent. You can check this rule in Prolog with a query: <code>cousins(X,Y), parent(R,X), parent(R, Y)</code>, it should return **false**
+    * remember: siblings are not cousins!
+  * aunt(X,Y) and uncle(X,Y) in terms of sister, brother and parent.
+  * half-orphan(X) --- a person with only one parent. TIP: celina is the only half-orphan in the KB
+  * widow(X) (and widower(X)) --- assume that all the single-parents are single because of the spouse's death. TIP: tobiasz is the only widower in the KB, there are no widows. In CLIPS you may check results of the following rule: <code>
+(defrule widower
+ ...
+=>
+ (assert (widower ?x))
+ (printout t ?x " is widower" crlf)
+)</code>. Do you get the expected result?
+===== 6. Tracking the execution of the program =====
+Since CLIPS doesn't correctly find the widowers, it is necessary to track the execution of the program:
+=== 6.1. Tracking the facts =====
+Allows you to track operations on facts: add, delete, change of the value.
+  - In the first step, we will start observing the **widower** rule to see what triggers it: <code> (watch rules widower) </code>
+  - We reset the fact base: <code> (reset) </code>
+  - Restart the inference: <code> (run) </code>
+  - Now we see the triggers and indexes of facts from which we started.
+  - Now check which fact triggered the inference: <code>(facts)</code>
+===== 6.2. Rule tracking =====
+Allows tracking of rules: firing, activation.
+  - Because we did learn nothing interesting tracing the fact, we will follow the **widow** rule and all the rules it depends on: **parent**, **marriage**: <code>
+(unwatch all)
+(watch rules marriage widow parent)
+</code>
+  - Now we reset the fact base: <code> (reset) </code>
+  - Restart the inference: <code> (run) </code>
+  - What is the reason behind the malfunction of the **widower** rule?
+  - How can we fix it?
+=== 6.3. Tracking in Prolog =====
+Prolog allows you to follow the program. To do so, you set the so-called. trace point.
+Trace points:
+  * ''trace/0'' - sets the trace point on all predicates, eg:
+<code>
+?- trace, woman(K), parent(K, _).
+</code>
+  * **trace/1** - sets the trace point at the indicated predicate,
+  * **trace/2** - modifies trace point of the specific events (call, redo, exit, fail), eg:
+    * remove the trace point from the specified predicate //something/1// <code> trace(something/1, -all) </code>
+    * set a trace point tracking only calls to the specified predicates //something// of arbitrary arity. <code>trace(something, call +)</code>
+  * Predicate ''debugging/0'' lists all the set trace points.
+  * The ''debug/0'' predicate activates debug mode.
+  * Predicate ''nodebug/0'' disactivates debug mode.
+Check following code:
+<code>
+?- trace(parent).
+[debug] ?- trace(mother).
+[debug] ?- trace(father)
+[debug] ?- parent(dariusz, tomasz).
+[debug] ?- nodebug.
+</code>

pl/dydaktyka/dss/rules/intro.1511872410.txt.gz · ostatnio zmienione: 2019/06/27 15:57 (edycja zewnętrzna)

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