For the following exercises, give a regular expression that represents that described set.2. The set of strings over (a, b, c) in which all the a's precede the b's, which in turnprecede the c's. It is possible that there are no a's, b's, or c's.3. The same as Exercise 2 without the null string.4. The set of strings over {a, b} that contain the substring aa and the substring bb.

Answered: For the following exercises, give a…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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For the following exercises, give a regular expression that represents that described set.
2. The set of strings over (a, b, c) in which all the a's precede the b's, which in turn
precede the c's. It is possible that there are no a's, b's, or c's.
3. The same as Exercise 2 without the null string.
4. The set of strings over {a, b} that contain the substring aa and the substring bb.

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Introduction:

A regular expression (regex) is a character sequence that defines a search pattern. Here's an example of a regular expression.

A regular expression (abbreviated regex or regexp; sometimes known as a rational expression) is a string of letters that indicates a search pattern in text. String-searching algorithms typically employ such patterns for "find" or "find and replace" operations on strings, as well as input validation.

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