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Unformatted text preview: CS 164, Midterm #1, Fall 1998 Fall 1998 Midterm #1 Professor Aiken Problem #1: Regular Expressions and Finite Automata a. In class we showed how to convert an NFA recognizing the language A Into an NFA recognizing the language A * . Given a machine recognizing A, the following construction adds epsilon transitions in both directions between the machine's start and final states (you may assume there is exactly one final state; there is always one start state in any case). Show that this construction is not a machine for A * . Your answer should be a DFA (not an NFA) accepting a language A that when modified according the construction does not recognize exactly A * . b. Give a regular expression for the set of all strings over 0 and 1 containing a pair of consecutive 0's and a pair of consecutive 1's. c. Give a DFA recognizing the set of all strings over 0 and 1 containing a pair of consecutive 1's followednot necessarily immediatelyby a pair of consecutive 0's....
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This note was uploaded on 05/17/2009 for the course CS 164 taught by Professor Staff during the Spring '08 term at Berkeley.
 Spring '08
 Staff
 Computer Science

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