(15) Let M be the language over {a, b, c, d, e, f} accepting all strings so that:1. There are precisely two e's in the string.2. Every a is immediately followed by an even number of b's.3. Every c is immediately followed by an odd number of f's.b's and f's don't occur except as provided in rules 2 and 3.5. All c's occur after the first e.4.6. All a's occur before the second e.7. In between the two e's there are exactly twice as many c's as a's.Construct a context-free grammar generating M. You do not need an inductive proof, but youshould explain how your construction accounts for each rule.5)We could eliminate one rule from M and make it regular. Which one? Why?(5) Show that the class of context free languages is not closed under intersection by finding twoCFLS whose intersection is not a CFL.

Answered: Image /qna-images/answer/75a488c8-ea91-4563-96fd-7624ebef9a72.jpg

15) Let M be the language over {a, b, c, d, e, f} accepting all strings so that: 1. There are precisely two e's in the string. 2. Every a is immediately followed by an even number of b's. 3. Every c is immediately followed by an odd number of f's. 4. b's and f's don't occur except as provided in rules 2 and 3. 5. All c's occur after the first e. 6. All a's occur before the second e. 7. In between the two e's there are exactly twice as many c's as a's.

15) Let M be the language over {a, b, c, d, e, f} accepting all strings so that: 1. There are precisely two e's in the string. 2. Every a is immediately followed by an even number of b's. 3. Every c is immediately followed by an odd number of f's. 4. b's and f's don't occur except as provided in rules 2 and 3. 5. All c's occur after the first e. 6. All a's occur before the second e. 7. In between the two e's there are exactly twice as many c's as a's.

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

See similar textbooks

Similar questions

Just need questions 4,5,6
5. i) Find the language L(G) overs, {a,b,c} generated by the grammer G with production: S-aSb, aS-Aa, Aab→c. ii) Write a grammer that generates the string over {a,b} not ending with ab.
Let E= {a, b}. Given regular expressions r = a*b*, r' = ba(ab)* + ab*ba* and r" = (a + b)aa(a + b)*, find L(r), L(r'), and L(r"), the languages defined by r, r', r", respectively.
Construct a regular expression defining each of the following languages over {a, b}; a. All strings such that the number of a’s is a multiple of 3. b. All strings such that the number of a’s is odd.
Do not copy from anywhere otherwise I'll give you multiple dislikes and will report. Other answers are wrong.
1. {w E {0, 1} *: w begins with 1 and, when interpreted as a binary number, is a multiple of 5} (since this DFA uses alphabet {0,1}, please flip our conventions and use states a, b, c, ...). *NOTE: Also include the language accepted by DFA as a set. 2. {w| w starts with an a and has at most one b} Draw DFA for each and make intersection of them. i.e, a. 1 DFA for start with an a b. 1 DFA for has at most one b c. 1 DFA for intersection of both of a and b
8. Build a DPDA that accepts the language L = {(ab)" (aab)b²" |n20
A) Design a RE for the language containing any number of a's and b's. B) Construct the RE for the language containing all the strings which end with 00 over the set Σ = {0,1} C) Construct the RE for the language consisting of the set of all strings of 0's and 1's beginning with 0 and ending with 1.
Generate a constrained Regular Expression for the language that is described by the following: 1) all strings MUST begin with at least one 'a' character 2) all strings MUST end with EXACTLY one 'a' 3) between the 'a' characters are an unknown number of 'b', 'c', and 'd' characters. 4) the number of 'c' characters are at least one. 5) the number of 'b' characters is exactly the same as the number of 'd' characters.
a) Construct CFG which accepts the strings of any number of a's followed by any number of b's, and ending with a.
Problem 3. (Regular Expressions-DFA) Show that the following languages are regular by giving a regular expression and DFA that describes each one: a) L1= {all strings over Σ= {0, 1} containing at least three 1's}. b) L2= {all strings over Σ = c) L3 = {all strings over Σ = d) L4= {all strings over Σ = e) L5= {all strings over Σ = {0, 1} that contain the substring 11 and the substring 00}. {0,1} that does not contain the substring 111}. {a,b,c} with length less than 2}. {a,b,c} in which the number of c's is divisible by 32}.
Q. Construct DFA’s for FollowingWhen  = {0, 1}v. Machine that accepts the language which has either odd number of 0’s or even number of 1’s but not both together .vi. Machine that accepts the language which has both 01 and 10 as substring .vii. Machine that accepts the language which has neither 00 nor 11 as a substring.