prolog ppt
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Prolog focuses on describing facts and relationships about problems rather than steps to solve problems. It uses facts to work out solutions by searching possible solutions. Facts are declared with a predicate followed by objects in parentheses separated by commas. Rules are used when a fact depends on other facts, with the head before the body separated by ":-". Variables begin with capital letters and are used to represent unknown values. Conjunction uses commas to represent "AND" and disjunction uses semicolons to represent "OR" between predicates.
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prolog ppt
- 2. Introduction PROgramming in LOGic Prolog focuses on describing facts and relationships about problems rather then on creating a series of steps to solve that problem. Emphasis on what rather than how It is widely used in the field of AI Basic Machine Logic Machine Problem in Declarative Form
- 3. FACTS Facts are statements about what is true about a problem, instead of instructions how to accomplish the solution. The Prolog system uses the facts to work out how to accomplish the solution by searching through the space of possible solutions. It is defined by an identifier followed by an n- tuple of constants. A relation identifier is referred to as a predicate.
- 4. Syntax for fact declaration Names of relationship and objects must begin with a lower-case letter. Relationship is written first (typically the predicate of the sentence). Objects are written separated by commas and are enclosed by a pair of round brackets. The full stop character ‘.’ must come at the end of a fact.
- 5. facts Predicate Interpretation valuable(gold) Gold is valuable. owns(john, gold) John owns gold. father(john ,mary) John is the father of Mary gives (john, book , mary) John gives the book to Mary Examples
- 6. RULES Rules are used when you want to say that a fact depends on a group of facts. Rule consist of a head and a body connected by the symbol :- (IF) eg. Likes(john, X) :- likes(X, wine). [ Head is satisfied if body is satisfied ] Here john likes every person who likes wine.
- 7. Syntax of rule <head> :- <body> Read ‘:-’ as ‘if’. likes(john,X) :- likes(X,cricket). “John likes X if X likes cricket”. i.e., “John likes anyone who likes cricket”. Rules always end with ‘.’
- 8. Variables Always begin with a capital letter ?- likes (john, X). ?- likes (john, Something). An instantiated variable is one that stands for an object. A variable begins with an uppercase letter or _ and can contain the same symbols as atoms. The same variable name used in 2 different questions represents 2 completely different variables. An uninstantiated variable can be used to search for any match.
- 9. Example Facts: () likes(john,mary). likes(john,X). % Variables begin with capital Queries ?- likes(X,Y). X=john, Y=Mary. % hit “;” for more ?- likes(X,X). X=john.
- 10. Example Rules likes(john,X) :- likes(X,wine). % :- = if likes(john,X):- female(X), likes(X,john). Query: ? - likes(john,Y). Y = bill ; no
- 11. Conjunction & Disjunction Conjunction of predicates is represented as a sequence of structures, separated by commas”,”. It is referred as “AND” sister_of (X,Y):- female (X), parents (X, M, F), Disjunction of predicates is represented as a sequence of structures, separated by semicolon”;”. It is referred as “OR” friend(ram,shyam):- friend(shyam,sita);friend(shyam,mohan).
- 12. THANK YOU