01122011.ppt

Intro to CLIPSPaula MatuszekCSC 9010, Spring, 2011 CLIPS History CLIPS = C Language Integrated Production System Developed at NASA in the 1980s C was used as implementation language (because of restricted availability of LISP compilers and problems of integration LISP-code with non-LISP applications) Initial version: a production rule interpreter. This is what we will use. Extensions include COOL: CLIPS Object-Oriented Language JESS: Java Expert Systems Shell Fuzzy Clips: Fuzzy logic, for capturing uncertainty What is it? Classic Rule-Based Expert System shell Core is facts and rules Inference is forward chaining using the RETE algorithm Multiple conflict resolution strategies Advantages: Written in C; portable, embeddable, fast Public domain, readily available Easy to set up, low initial effort Versions of CLIPS CLIPS is written in C = CLIPS is portable = there are different versions that run on different platforms: mac, unix, windows. Latest released version 6.24 can be downloaded from the CLIPS web site for Windows and OS X. There is a beta version 6.30, but we are not going to use it. Feel free to explore it if you wish. Download from / CLIPS Components A basic CLIPS program has three primary components: Facts Rules Agenda Facts represent information about the state of the world. Rules represent things to do with/about facts. CLIPS Facts Facts are what CLIPS believes to be true. The simplest form of a fact is a single string. (snowing) (“January 11”) An ordered fact is a list of one or more strings: (snowing “January 11”) Valid Facts Examples of valid ordered facts (single-field) (two fields) (speed 38 mph) (cost 78 dollars 23 cents) (name “John Doe”) Adding Facts Putting facts into the CLIPS fact base is done by asserting. CLIPS (assert(snowing)) Fact-1 This is the fact index. CLIPS (assert(snowing Jan11)) Fact-2 You can also ask CLIPS what facts it knows. CLIPS (facts) f-0 (initial-fact) f-1 (snowing) f-2 (snowing Jan11) For a