ProLog and Knowledge Representation: Part I

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ProLog and Knowledge Representation Part I

• Topics in Language Technology
• 2003

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Todays Lecture

• What is ProLog?
• Where does it come from?
• What is it good for?
• Facts, Rules and Queries Examples

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What is ProLog?

• ProLog stands for Programming in Logic.
• Pure ProLog is a declarative as opposed to a
  procedural programming language.
• Describe the problem situation and let the
  computer search for the solution.

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What is ProLog?

• ProLog Program
• Description of Problem Situation
• A set of facts and rules
• (i.e. a knowledge base)

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What is ProLog?

• Solving the problem running the program -
  asking a query.
• In terms of Logic if the content of the query is
  a logical consequence of the description of the
  problem situation then the program succeeds,
  otherwise it fails.

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Where does it come from?

• Created around 1970 by Alain Colmerauer and
  others at Marseille.
• Building on Logic Programming in which
  computation is viewed as controlled logical
  inferences (Robinson, 1965 Kowalski, 1979)

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What is it good for?

• Solving problems that involve symbolic
  representations of objects and relationships
  between objects.
• Colmerauer originally developed ProLog for
  language analysis and question-answering.

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What is it good for?

• Further applications
• mathematical theorem proving,
• expert systems,
• data bases,
• biochemical analysis/drug design,
• logistics,
• architectural design,

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Facts, Queries and Rules
pam
tom
parent
parent
parent
bob
liz
parent
parent
ann
pat
parent
jim
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Syntax

• A Prolog program is a list of facts and rules.
  The program is executed by querying it.
• unit clause predicate(term1,,termn)
• Fact predicate(term1,,termn).
• Rule unit clause -
• unit clause1,
• unit clausen.

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Syntax

• term variable or constant or
• functor(term1,,termn) or
• integer or list
• list termlist or or
  term1,,termn
• query ?- unit clause1, ,unit clausen.

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Practical

• Sicstus is installed in the computer suite
• You can start it via the Start/Programs/Computing
  menu select SICStus Prolog 3.10.1
• Free versions of Prolog
• http//www2.cs.cmu.edu/Groups/AI/html/faqs/lang/pr
  olog/prg/part2/faq-doc-2.html
• http//www.swi-prolog.org/

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Practical

• Online Prolog Book http//www.coli.uni-sb.de/kri
  s/learn-prolog-now/
• Exercises Lecture Slides
• http//www.itri.bton.ac.uk/teaching/PROLOG-2003/

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Practical Assignments

• Assignment 1 (40)
• Essay (2000-4000 words) on a topic that is
  chosen by the student from a list.
• HAND IN 3 Dec
• Assignment 2 (60)
• A PROLOG-related piece of work.
• HAND IN 28 Jan

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Practical Essay Writing

• Choose one topic only
• Write your own essay
• Be brief 4000 words can be worse than 2000
• Using material from publications is fine if you
• use quotations marks when you quote
• attribute the source when you paraphrase
• include the publication references (with page
  numbers) in both cases