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  1. /*References:
  2.  * https://w...content-available-to-author-only...c.uk/~mas02gw/prolog_tutorial/prologpages/
  3.  * 
  4.  * */
  5.  
  6. /************
  7.  * Facts
  8.  * Always start with lowercase letter, end with full stop
  9.  * You could use _ in facts (names), but please avoid math operators
  10. */
  11.  
  12. thanksgivingsoon.
  13. sunny.
  14. wanttoplay.
  15.  
  16. /*These are all facts. This whole page is your database for your facts & rules.
  17. You can also ask questions/query about your database.*/
  18.  
  19. /*Now, on the right side, after the ?- ask your first query:
  20.  * sunny.
  21.  * Hit run and see if the answer is yes
  22.  * the ?- means asking a question, it is already provided by this complier. 
  23.  * You would need to write it in other compliers in format: ?- sunny.
  24. */
  25.  
  26. /*Now, ask query: ?- raining.
  27.  * What is the output? */
  28.  
  29. /*__your answer here___*/
  30.  
  31. /*You can defind facts with arguments. (just like a function with input variables)
  32.  * It is just relationship between items.
  33.  * Relation names must begin with lowercase letter as well.*/
  34.  
  35. likes(mary,food).
  36. likes(mary,wine).
  37. likes(john,wine).
  38. likes(john,mary).
  39.  
  40. /*Ask query: ?- likes(mary,food).*/
  41.  
  42. /*__your answer here___*/
  43.  
  44. /*OK, some KOANS about facts: */
  45.  
  46. eats(fred,oranges).                           /* "Fred eats oranges" */
  47. /*__your answer here___*/                    /* "Fred eats T-bone steaks" */
  48. /*__your answer here___*/                           /* "Tony eats apples" */
  49. /*__your answer here___*/                         /* "John eats apples" */
  50.  
  51. /*Ask some queries on the right side:
  52.  * Does Fred eats T-bone steaks?
  53.  * ?- eats(tony,pears). means what? What is the result?*/
  54.  
  55. /*__your answer here___*/
  56.  
  57. /*You can also link up two sentances with ,
  58.  * Try query:
  59.  * ?- eats(fred,X),
  60.  * X=oranges
  61.  * What is the output? What is the meaning of this query?*/
  62. /*__your answer here___*/
  63.  
  64. age(ian,2).                   /*  Ian is 2 */
  65.  
  66. /*will query ?- age(ian, two). give yes? Why?*/
  67.  
  68. /*__your answer here___*/
  69.  
  70. /*************
  71.  * Variables
  72.  * With only the facts, we cannot really do anything productive with this PL.
  73.  * Just like other PLs, we need variables.
  74.  * Variables have to start with a CAPITAL letter
  75.  * The process of matching items with variables is known as unification.*/
  76. /*
  77.  * X: vairable X
  78.  * Myvar: another legal variable
  79.  * Myvar_current: also ok*/
  80.  
  81. /*What is the result of query ?- eats(fred,FoodX). ?
  82.  *Make sure you press next button to see all the results.
  83.  *In other editors, you would type ; to represent show next result.*/
  84.  
  85. /*__your answer here___*/
  86.  
  87. /***********
  88.  * Rules
  89.  * Each rule can have several variations -- clauses.
  90.  * Rules provide ways to get inferences about facts.
  91.  */
  92.  
  93. /*Operator :- means if*/
  94. mortal(X) :- 
  95.     human(X).  /*X is mortal if X is human*/
  96. human(petter).  /*give a fact that petter is a human*/
  97.  
  98. /*__your answer here___*/ /*Ask query: is petter mortal?*/
  99. /*What is the result of your query?*/
  100. /*__your answer here___*/
  101.  
  102. /*__your answer here___*/ /*Ask query: who is mortal?*/
  103. /*__your answer here___*/ /*What is the result of your query?*/
  104.  
  105. /*One rule can have several variations.
  106.  * The following example shows 3 ways that some thing is fun*/
  107.  
  108. fun(X) :-                      /* an item is fun if */ 
  109.         red(X),                /* the item is red */
  110.         car(X).                /* and it is a car */
  111. fun(X) :-                      /*  or an item is fun if */
  112.         blue(X),               /* the item is blue */
  113.         bike(X).               /* and it is a bike */
  114. fun(ice_cream).                /* and ice cream is also fun. */
  115.  
  116. /*Together with some facts:*/
  117. car(vw_beatle).
  118. car(ford_escort).
  119. bike(harley_davidson).
  120. red(vw_beatle).
  121. red(ford_escort).
  122. blue(harley_davidson).
  123.  
  124. /*__your answer here___*/ /*Ask query: is harley_davidson fun?*/
  125. /*__your answer here___*/ /*What is the result of your query?*/
  126. /*What are the logical steps that Prolog took to find the answer for you?
  127.  * Hint: start matching from the first fun clause.*/
  128. /*__your answer here___*/
  129.  
  130. /*__your answer here___*/ /*Ask query: What is fun?*/
  131.  
  132. /****************
  133.  * Recursion
  134.  */
  135. /*some facts:*/
  136. move(home,taxi,halifax). /*__your answer here___*/
  137. move(halifax,train,gatwick). /*__your answer here___*/
  138. move(gatwick,plane,rome). /*__your answer here___*/
  139.  
  140. /*on_route is a recursive predicate*/
  141. on_route(rome).
  142. on_route(Place):-       /*what does this mean?*/ /*__your answer here___*/
  143. 	move(Place,_Method,NewPlace), /*__your answer here___*/
  144. 	on_route(NewPlace).  /*__your answer here___*/
  145.  
  146. /* Query ?- on_route(home). is asking whether you can reach rome from home*/
  147. /*What are the steps that Prolog can use to find the answer for you?*/
  148. /*__your answer here___*/
  149.  
  150. /*Change _Method to Method, what will happen?*/
  151. /*By adding _ in front of a variable, we make it an anonymous variable and let the complier know 
  152.  * this var is not important so stop complaining about it.
  153.  * Does this remind you of some thing from F#?*/
  154.  
  155. /*****************
  156.  * List
  157.  */
  158. [a,b,c,d,e,f,g]. /*a list with simple facts*/
  159. /*__your answer here___*/ /*an empty list*/
  160. /*__your answer here___*/ /*a list with 3 names as facts*/
  161.  
  162. /*Just like F#, list in Prolog matches Head and Tail.*/
  163. p([H|T], H, T). /*bind/unify list [...] with head item H, and tail item T*/
  164. /*__your answer here___*/ /*What is the meaning of query ?-p([a,b,c], X, Y). ?*/
  165. /*__your answer here___*/ /*Output?*/
  166.  
  167. /*write queries to cut H and T out from the above 3 lists.*/
  168. /*__your answer here___*/
  169.  
  170. /*Search an item from a list, write down the meaning of each line:*/
  171. inList(Item,[Item,Rest]). /*__your answer here___*/
  172. inList(Item,[IgnoreHead|Tail]) :- /*__your answer here___*/
  173.     	inList(Item,Tail). /*__your answer here___*/
  174.  
  175. /*Write a query that test if apple is in the list [apple, pear, banana]*/
  176. /*__your answer here___*/
  177. /*What are the steps that Prolog can use to find the answer for you?*/
  178. /*__your answer here___*/
  179. /*Write a query that test if apple is in the list [pear, apple, banana]*/
  180. /*__your answer here___*/
  181. /*What are the steps that Prolog can use to find the answer for you?*/
  182. /*__your answer here___*/
  183.  
  184. /*Does this example reminds you of some thing from F#?*/
  185. /*__your answer here___*/
  186.  
  187.  
Compilation error #stdin compilation error #stdout 0s 0KB
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Standard input is empty
compilation info 
prog.pl:158: fatal error: redefining built-in predicate '.'/2
compilation failed
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Standard output is empty
https://ideone.com/LtFY6G
language:
Prolog (gprolog 1.4.5)
created:
4 years ago
visibility:
public

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