everybody:- father (X,Y), write (X,” is ” ,Y,”’s father\n” ), fail. Controlling Backtracking DOMAINS name=symbol PREDICATES nondeterm father(name,name) everybody CLAUSES father (ali, salem). These variables will be bounded before reaching the “not” expression containing themġ6. Should be placed around expressions which include only constants and /or bounded variables. OR howcanbuy (Person,Car,Way):- canbuy (Person,Car,Way),Way="cash" canbuy (Person, Car, Way), Way="takseet", NOT(canbuy (Person,Car,"cash")). canbuy ( Person,Car, “takseet”):- salary (Person, M), takseet(Car,T),M/3>=T/30. The isletter(X) predicate gives yes if X is a letter: PREDICATES isletter(char) CLAUSES isletter(Ch):- ‘a’=N.Note:The compound goal: multnum(7,5,X),addnum(X,X,Answer).
#Visual prolog free download how to
How to do arithmetic operations DOMAINS number=integer PREDICATES addnum(number,number,number) multnum(number,number,number) CLAUSES addnum(X,Y,S):- S=X+Y. Example: the query likes(X,Y), likes(Y,Z) will result in a type error, because Y will be matched to a game constant and can not replace a person variable in the second sub goal.ġ1. For example to express the likes relation: likes(person, game) We should first declare person in the domains section as follows: domains person,game= symbol predicates likes (person, game) Person and game are unknown domains(error) This declaration will allow prolog to detect type errors.It is used to define domains other than the built-in ones, also to give suitable meanings to predicate arguments.PROLOG will do the following matches and backtracking to the friends rule: For PROLOG to answer the query : friends (ali, P2).Rule’s symbol The head of the rule The body of the rule
![visual prolog free download visual prolog free download](http://docplayer.net/docs-images/59/43726054/images/146-0.png)
![visual prolog free download visual prolog free download](http://www.umbrella-soft.com/upload/bcc715a9d689ba399754a2e7cca458be.png)
To represent the rule that express the facts that two persons are friends if they both like the same game: friends( P1,P2):- likes (P1,G),likes (P2,G),P1P2.A rule consists of two parts: head and body separated by the symbol (:-).Rules are used to infer new facts from existing ones.If we put a goal like: drinks (samy,water).To add the fact that all persons drink water: drinks (Everyone, water).Assume we add the drinks facts to the likes database as follows: PREDICATES drinks(symbol, symbol) CLAUSES drinks(ali, pepsi).To find games liked by more than one person: likes (P1,Game),likes(P2,Game),P1P2.To find persons who like more than one game: likes(Person, G1),likes (Person,G2),G1G2.Person=ali Game=tennisĤ-Compound queries with multiple variables To list games liked by ali and ahmad likes (ali,Game),likes (ahmad,Game). To list persons who likes tennis and football, the goal will be likes( Person, tennis ),likes (Person, football).To know who likes what (i.e all likes facts) likes (Who,What).To know which person likes teniss likes (Who,tenis).To know all sports that ali likes: likes(ali,What).Then press Cntrl+G The output will be Yes or No for concrete questions 1.Ĝoncrete questions: (queries without variables) Example: GOAL likes(samir, handball).Yes Likes (samir,football).To supply a query in PROLOG put it in the goal section as follows: GOAL likes (ali, football).
![visual prolog free download visual prolog free download](https://html.pdfcookie.com/02/2019/12/31/r4296o5pkr2n/bg1c.jpg)
Predicates declared with the keyword nondeterm can fail and, in this case, do not produce any solution. defines non-deterministic predicates that can backtrack and generate multiple solutions.