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CSE240 Lecture 25

CSE240 Lecture 25

Introduction to Programming Languages
Programming with Prolog
(202011)

B546a9b97d993392e4b22b74b99b91fe?s=128

Javier Gonzalez
PRO

January 25, 2017
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  1. jgs CSE 240 Introduction to Programming Languages Lecture 25: Getting

    Started with Prolog Javier Gonzalez-Sanchez javiergs@asu.edu PERALTA 230U Office Hours: By appointment
  2. jgs Logic Programming Paradigm PROLOG

  3. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 3 jgs

    Paradigms
  4. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 4 jgs

    Summary Logic/Declarative Paradigm Key idea: A program is a set of facts about objects, rules about objects, and questions (queries) about the relations between objects. Features: • get rid of programming altogether.
  5. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 5 jgs

    Logic Paradigm § It focus on what is needed (requirements), instead of how to implement them. It just describe what the problem is and let the computer find a way to solve the problem, instead describing how to solve the problem. § It rely on the environment to find solutions that meet requirements. Answers / Results Queries Facts Rules
  6. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 6 jgs

    Prolog § PROLOG (PROgramming LOGic) § Interpreter. § Deductive database: set of statements and a deduction system. § Facts and Rules § Queries § Upper-Case variables § Lower-Case constants and names
  7. jgs Tools PROLOG

  8. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 8 jgs

    Install a Prolog Interpreter http://www.swi-prolog.org/download/stable
  9. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 9 jgs

    Local Prolog Interpreter To enter rules from the command line, type this : [user]. This puts you in a mode where you can enter facts and rules. Otherwise you get this kind of message: ERROR: Undefined procedure: (DWIM could not correct goal) You can then enter facts (or rules) e.g. : father(me,sarah). After having entered the knowledge, type CONTROL-D to come back to the mode where you can enter questions. Then you can ask: ?- father(me,X). X = sarah To quit: halt.
  10. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 10 jgs

    Online Prolog Interpreter
  11. jgs Getting Started PROLOG

  12. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 12 jgs

    Predicate Logic § It uses a simplified variation of predicate logic syntax, which is similar to natural language. § Predicate logic eliminate all unnecessary words from sentences, then transform the sentence by placing the relationship (predicate) first and grouping the objects (arguments) after the relationship predicate (object, object, object ....)
  13. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 13 jgs

    Predicate Logic § Facts: What is known, e.g., Bill likes car and bike, and he travels with one of them likes(bill, car), likes(bill, bike) travels(bill, car); travels(bill, bike) § Rules: What you can infer from the given facts. Rules enable you to infer facts from other facts, e.g., Bill is the father of Joe, if Joe is the son of bill. father(bill, joe) :- son(joe, bill). , means AND ; means OR
  14. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 14 jgs

    Natural Language Predicate Logic Type of Predicate A car is fast. fast(car). fact A rose is red. red(rose). fact Bill likes the car if the car is fast. likes(bill, car) :- fast(car). rule Humidity is high if it rains high(humidity):- rains(). rule Jane is mother of Elaine mother_of(jane, elaine). fact Jane is mother of Mike mother_of(jane, mike). fact David is father of Jesse father_of(david, jesse). fact Jesse is father of Obed father_of(jesse, obed). fact Grandmother X of Z if (X is mother of Y and (Y is mother of Z or Y is father of Z) grandmother_of(X, Z) :- mother_of(X, Y), ( mother_of(Y, Z); father_of(Y, Z) ). rule
  15. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 15 jgs

    Simple Facts § Facts and rules creates a database, so, step 1, provide data % facts: exam_easy. arizona_hot. july_4_is_independence_day. § step 2, run queries ?- exam_easy. true ?- arizona_hot. true ?- july_4_is_independence_day true
  16. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 16 jgs

    Facts with Arguments likes(john,mary). eats(fred,oranges). age(john,32). age(ian,2). ?- eats(fred,oranges). true ?- eats(mike,apples). false ?- age(ian,two). false
  17. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 17 jgs

    Facts with Arguments likes(john,mary). eats(fred,oranges). age(john,32). age(ian,2). ?- eats(fred,X). X = oranges ?- eats(mike,X). false ?- age(ian,Y). Y = 2 ?- likes (WhoX, WhoY). WhoX = john, WhoY = mary
  18. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 18 jgs

    Facts and Rules % rules and facts: mortal(X) :- human(X). human(socrates). ?- mortal(socrates). true ?- mortal(P). P = socrates
  19. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 19 jgs

    A program is Facts, Rules … % facts instructor(john,cs365). instructor(mary,cs311). instructor(paul,cs446). enrolled(joseph,cs311). enrolled(joseph,cs365). enrolled(joseph,cs446). enrolled(danielle,cs365). enrolled(danielle,cs446). % rules teaches(P,S) :- instructor(P,C), enrolled(S,C). classmates(S1, S2) :- enrolled(S1, C), enrolled(S2, C).
  20. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 20 jgs

    … and Queries (part 1 / 2) ?- enrolled (joseph, cs365). true ?- enrolled (X, cs365). X=joseph X=danielle ?- teaches (X, joseph). X=john X=mary X=paul ?- classmates (joseph, danielle). true ?- classmates (joseph, jessica). false ?- classmates (jessica, danielle). false
  21. Javier Gonzalez-Sanchez | CSE240 | Spring 2020 | 21 jgs

    … and Queries (part 2 / 2) % An additional rule classmates (S1, S2, C) :- enrolled (S1, C), enrolled (S2, C) ?- classmates (joseph, danielle, C). cs365 cs446 ?- classmates (joseph, jessica, C). false ?- classmates (jessica, danielle, C). false
  22. jgs CSE 240 Introduction to Programming Languages Javier Gonzalez-Sanchez javiergs@asu.edu

    Spring 2020 Disclaimer. These slides can only be used as study material for the class CSE240 at ASU. They cannot be distributed or used for another purpose.