1 / 10

Notes for Week 12

Notes for Week 12. The AI War LISP and Prolog Basic Concepts of Logic Programming. The AI War. Two main schools of thought on how machines should learn: inductive and deductive analysis .

michon
Download Presentation

Notes for Week 12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Notes for Week 12 The AI War LISP and Prolog Basic Concepts of Logic Programming

  2. The AI War • Two main schools of thought on how machines should learn: inductive and deductive analysis. • Deductive: Expert => rules => knowledge, top-down approach, expert systems used LISP, Prolog, and shell languages CLIPS and JESS; programs suffered from: brittle and expensive to maintain • Inductive: knowledge <= rules <= Data, bottom-up, machine learning and data mining – extracts patterns from data and learns from examples, such as DT, ANN, GA; starting from 1980’s

  3. Logic Programming • Logic is used to represent program • Deductions are used as computation • Historical notes: predicate calculus, unification, resolution principle, Prolog • Differences between procedural programming and logic programming

  4. Resolution • An important rule of inference that can applied to • clauses (wff consisting of disjunction of literals) • a refutation system: prove by contradiction • Idea: given two clauses, we can infer a new clause by taking the disjunction of the two clause & eliminating the complementary pair of literals

  5. A refutaion system Given a set of clauses S & and goal G, * negate the goal G *{S} U {¬G} * existence of contradiction => derivation of empty clause Based on {S} U {¬G} is inconsistent if {S} U {G} is consistent

  6. Resolution in a nutshell • Based on • Clause form of predicate logic • Inconsistence checking (refutation) • The heart of the rule is the unification algorithm (the process of finding substitutions for variables to make arguments match )

  7. Forward/backward chaining • A group of multiple inferences that connect a problem with its solution is called a chain • Forward chaining: inference starts from facts/rules • Backward chaining: inference starts from given problems

  8. Backtracking technique • Inference backtracks to a previous step when a failure occurs. • Naïve backtracking: backtracks mechanically to the most recent step when a failure occurs • Intelligent backtracking: analyze the cause of a failure & backtracks to the source of values causing the failure

  9. Concept questions • What are the motivations for logic programming? • What are the differences between procedural programming and logic programming? • What is deductive analysis? Illustrate with an example. • What is inductive analysis? Illustrate with an example. • Execution of a Prolog program: knowledge representation and computation

  10. Concept Questions • What are resolution, unification, instantiation? • Is Prolog forward chaining? • What is the deduction trees of resolution? • Programming in Prolog: • asserting facts, • representing knowledge in rules, • asking questions about objects and relations

More Related