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Unformatted text preview: CPSC 121 Lecture 34 April 3, 2009 Menu April 3, 2009 Topics: Regular Expressions and DFAs (revisited) Reading: Today: Epp 12.1 Lab 8 prep Reminders: Assignment 4 due TODAY (by 17:00) Teaching evaluation survey now available online deadline 23:00 April 12 TA teaching evaluation inclass Monday, April 6 Assignment/quiz/midterm return inclass Monday, April 6 Review session (Steve): Thu April 9, 9:00, DMP 310 Review session (Bob): Thu April 16, 14:00, DMP 110 Final exam Friday, April 17, 7:00pm, SRC A READ the WebCT Vista course announcements board Language Defined by a Regular Expression Let be a given (finite) alphabet. The function L that associates a language to each regular expression, r , over is defined below. L ( r ) is called the language defined by r 1. Base cases: L ( ) = , L ( ) = { } , a , L ( a ) = { a } 2. Recursive cases: If L ( r ) and L ( s ) are languages defined by regular expressions r and s over , then L ( rs ) = L ( r ) L ( s ) L ( r  s ) = L ( r ) L ( s ) L ( r * ) = ( L ( r )) * Given a regular expression, r , one can determine the (formal) language defined by...
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This note was uploaded on 01/09/2010 for the course CPSC 121 taught by Professor Belleville during the Spring '08 term at The University of British Columbia.
 Spring '08
 BELLEVILLE

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