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Introduction to CLIPS (Lecture Note #17)

Introduction to CLIPS (Lecture Note #17). 인공지능 이복주 단국대학교 컴퓨터공학과. Outline. Expert Systems: Principles and Programming, Joseph Giarratano & Gary Riley, PWS Publishing Company, 1998 Chapter 7 Introduction to CLIPS Chapter 8 Pattern Matching Introduction to Expert Systems, Peter Jackson

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Introduction to CLIPS (Lecture Note #17)

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  1. Introduction to CLIPS(Lecture Note #17) 인공지능 이복주 단국대학교 컴퓨터공학과

  2. Outline • Expert Systems: Principles and Programming, Joseph Giarratano & Gary Riley, PWS Publishing Company, 1998 • Chapter 7 Introduction to CLIPS • Chapter 8 Pattern Matching • Introduction to Expert Systems, Peter Jackson • Appendix CLIPS Programming

  3. Introduction • Three types of programming paradigms in CLIPS • Rule-based • Object-oriented • Procedural • Will focus on rule-based • Three components: fact list, knowledge base (rules), inference engine

  4. CLIPS • Support rule-based, object-oriented, and procedural programming • Programming language style is similar to OPS5, but more powerful • Support only forward chaining rules • Not backward chaining • COOL: CLIPS Object-Oriented Language • Extension of Common Lisp Object System (CLOS) • Syntactically similar to LISP

  5. CLIPS • CLIPS: C Language Integrated Production System • Designed at NASA Johnson Space Center, mid-80s • High portability, low cost, easy integration with external system • Original CLIPS supported only rule-based (note: Production System) • CLIPS version 5.0 added procedural and OO • Due to its portability, installed various computers from PCs to CRAY • Runs on UNIX, DOS, Windows, and Macintosh • Maintained as public domain software • E.g., http://www.cosmic.uga.edu • Downloadable by anonymous ftp • e.g., http://www-cgi.cs.cmu.edu/afs/cs/project/ai-repository/ai/areas/expert/systems/clips

  6. Notation • (example) • (example [1]) ; optional • (example) • (example 1) • (example <integer>) • <> means replacement • (example 1) • (example 5) • (example –20) • <integer>* • * means zero or more • 1 • 1 2 • 1 2 3

  7. Notation • <integer>+ • + means one or more • <integer>+ is same as <integer> <integer>* • All | none | some • | indicates a choice

  8. Field • Tokens • Group of characters • Some tokens consist of one character: e.g., ‘(‘, ‘)’ • Field: special tokens • Seven types of field • Float, integer, symbol, string, external address, instance name, instance address • Numerical fields: Float, integer • Float: 1.5, 1.0, 0.7, 9e+1, 3.5e10 • Integer: 1, +3, -1, 65 • Symbol • Starts with printable ASCII character, followed by zero or more characters

  9. Field • Delimiters • Any non-printable ASCII characters (spaces, tabs, CRs, LFs) • “ (double quote) • ( (opening parenthesis) • ) (closing parenthesis) • ; (semi colon) • & (ampersand) • | (vertical bar) • ~ (tilde) • < (less than) • ?, $: variable • Cannot be placed at the beginning of a symbol

  10. Field • Examples of valid symbols • Space-Station • February • fire • Activate_sprinkler_system • notify-fire-department • !?#$^* • 345B • 346-95-6156 • Case-sensitive • Case-sensitive • Case-Sensitive • CASE-SENSITIVE are different symbols

  11. Field • String • Begin and end with double quotation • Examples of valid strings • “Activate the sprinkler system.” • “!?#$^” • “John Q. Public” • Spaces in a string are preserved • “spaces” • “spaces “ • “ spaces” • “ spaces “ are different strings • “”three-tokens”” • “” • three-tokens • “”

  12. Field • “\”single-token\”” • “”single-token””: one string field • “\\single-token\\” • “\single-token\”: one string field • External addresses, instance addresses, instance names • Of little interest in rule-based • Multi-field value • Zero or more fields • When calling a function • (): zero length multi-field • (this that): multi-field containing the symbols this and that

  13. Entering and Exiting CLIPS • CLIPS> • CLIPS prompt • Top level: Commands can be entered directly • (exit): exiting command • Vs. exit: a symbol • Parentheses should be matched and balanced • ex<enter-key>it • Two tokens: ex and it • A command sequence • CLIPS> exit ; exit is a symbol • exit • CLIPS> (+ 3 4) ; a function • 7 • CLIPS> (exit) ; exit command

  14. Facts • Facts consists of • Relation name: a symbolic field • Zero or more slots: also symbolic fields • Associated values • Example • (person (name “John Q. Public”) • (age 23) • (eye-color blue) • (hair-color black)) • Order of slots are irrelevant • (person (hair-color black) • (name “John Q. Public”) • (age 23) • (eye-color blue) • is the same as above

  15. Deftemplate Construct • Deftemplate construct • Groups of facts share the same relation name • The common information is described • Analogous to a record structure in Pascal and C • General format • (deftemplate <relation-name> [<optional-comment>] <slot-definition>*) • <slot-definition> • (slot <slot-name>) | (multislot <slot-name>) • Person fact • (deftemplate person “An example deftemplate” • (slot name) • (slot age) • (slot eye-color) • (slot hair-color))

  16. Multi-field Slots • Place one or more fields into a given slot • Person deftemplate • (deftemplate person “An example deftemplate” • (multislot name) • (slot age) • (slot eye-color) • (slot hair-color)) • Person fact • (person (name John Q. Public) • (age 23) • (eye-color blue) • (hair-color black))

  17. Ordered Facts • Ordered facts • Does not have a corresponding deftemplate • Slot name is not required • Example • (number-list 7 9 3 4 20) • Equivalent to • (deftemplate number-list (multislot values) • (number-list (values 7 9 3 4 20))

  18. Adding and Removing Facts • Facts are added and removed from the fact list • Assert command: add a fact • (assert <fact>+) • Example • CLIPS> • (deftemplate person • (slot name) • (slot age) • (slot eye-color) • (slot hair-color)) • CLIPS> • (assert (person (name “John Q. Public”) • (age 23) • (eye-color blue) • (hair-color black))) • <Fact-0> ; assert returns a value • CLIPS>

  19. Adding and Removing Facts • Facts command • (facts) • Displays the facts in the fact list • Example • CLIPS> (facts) • f-0 (person (name “John Q. Public”) • (age 23) • (eye-color blue) • (hair-color black)) • For a total of 1 fact. • CLIPS> • f-0: fact identifier • 0: fact index

  20. Adding and Removing Facts • Duplicate facts are not allowed • Adding another facts • CLIPS> • (assert (person (name “Jane Q. Public”) • (age 36) • (eye-color green) • (hair-color red))) • <Fact-1> • CLIPS> (facts) • f-0 (person (name “John Q. Public”) • (age 23) • (eye-color blue) • (hair-color black)) • f-1 (person (name “Jane Q. Public”) • (age 34) • (eye-color green) • (hair-color red)) • For a total of 2 facts. • CLIPS>

  21. Adding and Removing Facts • Adding more than one facts • (assert (person (name “Jane Q. Public”) • (age 36) • (eye-color green) • (hair-color red)) • (person (name “Jane Q. Public”) • (age 34) • (eye-color green) • (hair-color red)))

  22. Adding and Removing Facts • Viewing a portion of fact list • (facts [<start> [<end> [<maximum>]]]) • No more than <maximum> facts are displayed • Removing a fact • The deleted fact identifier will be missing • Called retraction • (retract <fact-index>+) • (retract 0) ; John Q. Public removed • (retract 1) ; Jane Q. Public removed • Removing non-existent fact • CLIPS> (retract 1) • CLIPS> (retract 1) • [PRNTUTIL1] Unable to find fact f-1. • CLIPS> • Retract multiple facts • (retract 0 1)

  23. Modifying and Duplicating Facts • Modify command • Slot values of deftemplate facts can be modified • (modify <fact-index> <slot-modifier>+) • <slot-modifier> • (<slot-name> <slot-value>) • Example: John Q. Public’s age is increased • CLIPS> (modify 0 (age 24)) • <Fact-2> • CLIPS> (facts) • f-2 (person (name “John Q. Public”) ; new index • (age 24) • (eye-color blue) • (hair-color black)) • For a total of 1 fact. • CLIPS>

  24. Modifying and Duplicating Facts • Duplicate command • Same as modify except • does not retract the original fact • Example • CLIPS> (duplicate 2 (name “Jack S. Public”)) • <Fact-3> • CLIPS> (facts) • f-2 (person (name “John Q. Public”) • (age 24) • (eye-color blue) • (hair-color black)) • f-3 (person (name “Jack S. Public”) • (age 24) • (eye-color blue) • (hair-color black)) • For a total of 2 facts. • CLIPS>

  25. Watch command For debugging (watch <watch-item>) <Watch-item> One of the symbols: facts, rules, activations, statistics, compilations, focus, all Example CLIPS> (facts 3 3) f-3 (person (name “Jack S. Public”) (age 24) (eye-color blue) (hair-color black)) For a total of 1 fact. CLIPS> (watch facts) CLIPS> (modify 3 (age 25)) <== f-3 (person (name “Jack S. Public”) (age 24) (eye-color blue) (hair-color black)) ==> f-4 (person (name “Jack S. Public”) (age 25) (eye-color blue) (hair-color black)) <Fact-4> CLIPS> Unwatch (unwatch <watch-item) The Watch Command

  26. Deffacts Construct • Assert a set of facts • (deffacts <deffacts name> [<optional comments>] <facts>*) • example • (deffacts people “Some people we know” • (person (name “John Q. Public”) (age 24) • (eye-color blue) (hair-color black)) • (person (name “Jack S. Public”) (age 24) • (eye-color blue) (hair-color black)) • (person (name “Jane Q. Public”) (age 36) • (eye-color green) (hair-color red))) • Assert the deffatcs statement • (reset)

  27. Deffacts Construct • Example • CLIPS> (unwatch facts) • CLIPS> (reset) • CLIPS> (facts) • f-0 (initial-fact) ; new fact by reset command • f-1 (person (name “John Q. Public”) (age 24) • (eye-color blue) (hair-color black)) • f-2 (person (name “Jack S. Public”) (age 24) • (eye-color blue) (hair-color black)) • f-3 (person (name “Jane Q. Public”) (age 36) • (eye-color green) (hair-color red)) • For a total of 4 facts. • CLIPS>

  28. The Components of a Rule • A rule example • In an industrial plant monitoring expert system • IF the emergency is a fire • THEN the response is to activate the sprinkler system • Define template for the emergency and response • (deftemplate emergency (slot type)) • type could be fire, flood, power outage • (deftemplate response (slot action)) • Define rule • (defrule fire-emergency “An example rule” • (emergency (type fire)) • => • (assert (response (action activate-sprinkler-system)))) • General format • (defrule <rule name> [<comment>] • <pattern>* ; LHS of the rule • => • <actions>*) ; RHS of the rule

  29. The Agenda and Execution • Agenda • The collection of activated rules • Salience • The priority of a rule in integer • Run command • (run <limit>) • <limit>: maximum number of rules to be fired • Displaying the agenda • (agenda) • Example • CLIPS> (reset) • CLIPS> (assert (emergency (type fire))) • <Fact-1> • CLIPS> (agenda) • 0 fire-emergency: f-1 ; salience, rule, fact • For a total of 1 activation. • CLIPS>

  30. Rules and Refraction • Run command • CLIPS> (run) • CLIPS> (facts) • f-0 (initial-fact) • f-1 (emergency (type fire)) • f-2 (response (action activate-sprinkler-system)) • For a total of 3 facts. • CLIPS> • refraction • Rules are not fired more than once for a specific set of facts • (clear) • removes all constructs and all facts • Vs. (reset) asserts the deffacts statement

  31. The Printout Command • Printout command • (printout <logical-name> <print-items>*) • Example • (defrule fire-emergency • (emergency (type fire)) • => • (printout t “Activate the sprinkler system” crlf)) • ; t: terminal, destination name • Using multiple rules • (defrule flood-emergency • (emergency (type flood)) • => • (printout t “Shut down electrical equipment” crlf))

  32. Using Multiple Patterns • Rules with multiple patterns • (deftemplate extinguisher-system • (slot type) • (slot status)) • (defrule class-A-fire-emergency • (emergency (type class-A-fire)) • (extinguisher-system (type water-sprinkler) • (status off)) • => • (printout t “Activate water sprinkler” crlf)) • (defrule class-B-fire-emergency • (emergency (type class-B-fire)) • (extinguisher-system (type carbon-dioxide) • (status off)) • => • (printout t “Use carbon dioxide extinguisher” crlf))

  33. Loading and Saving Construct • Loading constructs from a file • (load <file-name>) • E.g., (load “fire.clp”) • Watching compilation • CLIPS> (load “fire.clp”) • Defining deftemplate: emergency • Defining deftemplate: response • Defining defrule: fire-emergency • TRUE • CLIPS> • No watch • CLIPS> (clear) • CLIPS> (unwatch compilations) • CLIPS> (load “fire.clp”) • %%* ; % for defconstruct * for rule • TRUE • CLIPS>

  34. Saving Construct to a File • (save <file-name>) • E.g., (save “fire.clp”) • Saves all the constructs • Saving partial constructs • Use an text editor

  35. Variables • Variables • Question mark followed by symbol • e.g., ?speed, ?sensor, ?value, ?noun, ?color • Bind • Assignment of a value to a variable

  36. Example CLIPS> (clear) CLIPS> (deftemplate person (slot name) (slot eyes) (slot hair)) CLIPS> (defrule find-blue-eyes) (person (name ?name) (eyes blue)) => (printout t ?name “ has blue eyes.” crlf)) CLIPS> (deffacts people (person (name Jane) (eyes blue) (hair red)) (person (name Joe) (eyes green) (hair brown)) (person (name Jack) (eyes blue) (hair black)) (person (name Jeff) (eyes green) (hair brown))) CLIPS> (reset) ; Assert the deffatcs CLIPS> (run) Jack has blue eyes. Jane has blue eyes. CLIPS> Variables

  37. Blocks World • Blocks world initial configuration • Facts about which blocks are on top of others • (deftemplate on-top-of • (slot upper) • (slot lower)) • (on-top-of (upper A) (lower B)) • (on-top-of (upper B) (lower C)) • (on-top-of (upper D) (lower E)) • (on-top-of (upper E) (lower F)) • (on-top-of (upper nothing) (lower A)) • (on-top-of (upper C) (lower floor)) • (on-top-of (upper nothing) (lower D)) • (on-top-of (upper F) (lower floor)) A D Goal: C on top of E B E C F

  38. Blocks World • Floor and nothing are not blocks • (block A) • (block B) • (block C) • (block D) • (block E) • (block F) • Describe the goal • (deftemplate goal (slot move) (slot on-top-of)) • (goal (move C) (on-top-of E)) • on-top-of was also a template name in the prev page • Initial state • (deffatcs initial-state • (block A) • … • (on-top-of … • … • (goal (move C) (on-top-of E))) A D B E C F

  39. Blocks World block1 • Move-directly rule • (defrule move-directly • ?goal <- (goal (move ?block1) • (on-top-of ?block2)) • (block ?block1) • (block ?block2) • (on-top-of (upper nothing) (lower ?block1)) • ?stack-1 <- (on-top-of (upper ?blocks1) (lower ?block3)) • ?stack-2 <- (on-top-of (upper nothing) (lower ?block2)) • => • (retract ?goal ?stack-1 ?stack-2) • (assert (on-top-of (upper ?block1) (lower ?block2)) • (on-top-of (upper nothing) (lower ?block3))) • (printout t ?block1 “moved on top of “ ?block2 “.” crlf)) block3 block2

  40. Blocks World block1 • Move-to-floor rule • (defrule move-to-floor • ?goal <- (goal (move ?block1) • (on-top-of floor)) • (block ?block1) • (on-top-of (upper nothing) (lower ?block1)) • ?stack <- (on-top-of (upper ?block1) (lower ?block2)) • => • (retract ?goal ?stack) • (assert (on-top-of (upper ?block1) (lower floor)) • (on-top-of (upper nothing) (lower ?block2))) • (printout t ?block1 “moved on top of floor.“ crlf)) block2

  41. Blocks World block2 block1 • Clear-upper-block rule • (defrule clear-upper-block • (goal (move ?block1)) ; move is a slot of goal • (block ?block1) • (on-top-of (upper ?block2) (lower ?block1)) • (block ?block2) • => • (assert (goal (move ?block2) (on-top-of floor)))) • Clear-lower-block rule (actually clear the top of block) • (defrule clear-lower-block • (goal (on-top-of ?block1)) ; on-top-of is a slot of goal • (block ?block1) • (on-top-of (upper ?block2) (lower ?block1)) • (block ?block2) • => • (assert (goal (move ?block2) (on-top-of floor))))

  42. Blocks World • Run • CLIPS> (reset) • CLIPS> (run) • A moved on top of floor. • B moved on top of floor. • D moved on top of floor. • C moved on top of E. • CLIPS> A D B E C F

  43. Functions and Expressions • Elementary math functions • CLIPS> (+ 2 2) • 4 • CLIPS> (/ 2 3) • 0.666667 • CLIPS> (+ 2 3.0) • 5.0 • CLIPS> (+ 2 3 4) • 9 • CLIPS> (- 2 3 4) • -5 • CLIPS> (+ 2 (* 3 4)) • 14

  44. Functions and Expressions • Embed the expression within other expressions • CLIPS> (clear) • CLIPS> (assert (answer (+ 2 3))) • <Fact-0> • CLIPS (facts) • f-0 (answer 4) • For a total of 1 fact. • CLIPS> • Function names are also symbols • CLIPS> (clear) • CLIPS> (assert (expression 2 + 3 * 4)) • <Fact-0> • CLIPS> (facts) • f-0 (expression 2 + 3 * 4) • For a total of 1 fact. • CLIPS>

  45. I/O Functions • The read function • CLIPS> (clear) • CLIPS> • (defrule get-first-name • => ; no pattern • (printout t “What is your first name? “) • (bind ?response (read)) • (assert (user’s-name ?response))) • CLIPS> (reset) • CLIPS> (run) • What is your first name? Gary • CLIPS> (facts) • F-0 (initial-fact) • F-1 (user’s-name Gary) • For a total of 2 facts. • CLIPS>

  46. I/O Functions • Open function • (open <file-name> <file-ID> [,file-access.]) • E.g., (open “input.dat” data “r”) • Can use “w”, “r+”, “a” also • Close function • (close [<file-ID>]) • E.g., (close data) • Writing to a file • CLIPS> (open “example.dat” example “w”) • TRUE • CLIPS> (printout example “green” crlf) • CLIPS> (printout example 7 crlf) • CLIPS> (close example) • TRUE • CLIPS>

  47. I/O Functions • Reading from a file • CLIPS> (open “example.dat” example “r”) • TRUE • CLIPS> (read example) • green • CLIPS> (read example) • 7 • CLIPS> (read example) • EOF • CLIPS> (close example) • TRUE • CLIPS>

  48. I/O Functions • The readline function • CLIPS> (clear) • CLIPS> • Defrule get-name • => • (printout t “What is your name? “) • (bind ?response (readline)) • (assert (user’s-name ?response))) • CLIPS> (reset) • CLIPS> (run) • What is your name? Gary Riley • CLIPS> (facts) • F-0 (initial-fact) • F-1 (user’s-name “Gary Riley”) • For a total of 2 facts. • CLIPS>

  49. I/O Functions • The readline function with multi-field • CLIPS> (clear) • CLIPS> • Defrule get-name • => • (printout t “What is your name? “) • (bind ?response (explode$ (readline))) • (assert (user’s-name ?response))) • CLIPS> (reset) • CLIPS> (run) • What is your name? Gary Riley • CLIPS> (facts) • F-0 (initial-fact) • F-1 (user’s-name Gary Riley) • For a total of 2 facts. • CLIPS>

  50. Summary • Expert Systems: Principles and Programming, Joseph Giarratano & Gary Riley, PWS Publishing Company, 1998 • Chapter 7 Introduction to CLIPS • Chapter 8 Pattern Matching • Introduction to Expert Systems, Peter Jackson • Appendix CLIPS Programming

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