cs373 fa10 hw3

# cs373 fa10 hw3 - CS 373: Theory of Computation Assigned:...

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Problem Set 3 CS 373: Theory of Computation Assigned: September 14, 2010 Due on: September 21, 2010 at 10am Instructions: This homework has two parts. The ﬁrst part has practice problems from the textbook many of whose solutions can be found in the textbook itself; you must not turn in solutions for these. The second part has 3 problems that can be solved in groups of size at most 3. Please strictly follow the homework guidelines given on the class website; submitions not following these guidelines will not be graded. Recommended Reading: Lectures 6 and 7 and pages 63 through 76 of class textbook. Practice Problems Solve problems 1.18(a), 1.19(a), 1.20, 1.21 (a) and 1.23 of class textbook. Homework Problems Problem 1 . [Category: Comprehension+Design] 1. Describe the language of the following regular expressions. A clear, crisp one-level interpretable English description is acceptable, like “This is the set of all binary strings with at least three 0s and at most hundred 1s”, or like “ { 0 n (10) m | n and m are integers } ”.A vague, recursive or multi-level-interpretable description is not, like “This is a set of binary strings that starts and ends in 1, and the rest of the string starts and ends in 0, and the remainder of the string is a smaller string of the same form!” or “This is a set of strings like 010, 00100, 0001000, and so on!”. You need not prove the correctness of your answer. (a) (0 * 1 1 * ) * [1 points] (b) (1 ± )(00 * 1) * 0 * [2 points] (c) 0 * (1 000 * ) * 0 * [2 points] 2. Give regular expressions that accurately describe the following languages. You need not prove the correctness of your answer. (a) All binary strings such that if it starts with 0 it has odd length and if it starts with 1 it has even

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## This note was uploaded on 10/04/2011 for the course CS 373 taught by Professor Viswanathan,m during the Fall '08 term at University of Illinois, Urbana Champaign.

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cs373 fa10 hw3 - CS 373: Theory of Computation Assigned:...

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