COSC 4760
Computer Networks
November 24, 2014
Exam 3
Students Name:
ANSWER KEY
This is a closed book examination. The use of notes, texts, or other reference material,
including but not limited to electronic storage, access, or data processing devices is

CS 162
Fall 2015
Homework 5 Solutions
October 30, 2015
Timothy Johnson
1. Exercise 6.3.2 on page 251 of Hopcroft et al.
Convert the grammar
S 0S1 | A
A 1A0 | S |
to a PDA that accepts the same language by empty stack.
We follow the construction given in

CS 341: Foundations of Computer Science II
Prof. Marvin Nakayama
Homework 7 Solutions
1. Give an implementation-level description of a Turing machine that decides the language
B = cfw_ 0n 1n 2n | n 0 .
Answer:
M = On input string w:
1. Scan the input from

CS 162
Fall 2015
Homework 4 Problems
October 21, 2015
Timothy Johnson
1. Let L = cfw_0n 12n |n > 0 Give a CFG for L.
The following CFG will produce L.
S 0S11 | 011 |
2. Show that every regular language L is also context free. Hint: use a proof by inducti

CS 341: Foundations of Computer Science II
Prof. Marvin Nakayama
Homework 10 Solutions
1. If A m B and B is a regular language, does that imply that A is a regular language?
Answer: No. For example, define the languages A = cfw_ 0n 1n | n 0 and B = cfw_1

Learning Outcomes
Explain Groups of Layers
Explain Network Standards
Explain Why Network Standards
Explain Standard Making Process
Explain Formal Standardisation and its stages
Explain De Facto Standards
Explain International Standard Setting
Organisation

Sn 3: Learning
Outcomes
Types
of Networks: General
Future Trends
Communications media (satellite,
microwave, radio, fibre, coax)
characteristics, advantages and
disadvantages of each
Some LAN Standards: 10BaseT,
100BaseT, 1000BaseT,100BaseF,
1000BaseF

W3-1:Learning
Outcomes
Transmission
Time/Propagation time
and its implications?
What is coding (Morse Code, ASCII,
EBCDIC)
Explain Digital and Analogue definitions
Advantages of digital vs. analogue
Explain Frequency, Band, Bandwidth,
Baud rate, Bit

Hardware Fundamentals
Week 7 Lesson 1
10/09/16
Hardware Fundamentals
1
Learning Outcomes
Define Visual Display Unit (VDU) characteristics: Pixel, Resolution,
Screen size and Refresh Rate
Describe briefly the purpose of video standards.
Discuss different v

CS 162
Fall 2015
Homework 8 Solutions
December 8, 2015
Timothy Johnson
1. Suppose an oracle has given you a magic computer, C, that when given any Boolean formula
B in CNF will tell you in one step whether B is satisfiable. Show how to use C to construct

CS 162
Fall 2015
Homework 3 Problems
October 13, 2015
Timothy Johnson
1. Let L be the language of all string of balanced parentheses, that is, all strings of the characters
( and ) such that each ( has a matching ). Use the Pumping Lemma to show that
L is

CS 341: Foundations of Computer Science II
Prof. Marvin Nakayama
Homework 8 Solutions
1. Consider the decision problem of testing whether a DFA and a regular expression are
equivalent. Express this problem as a language and show that it is decidable.
Answ

SOLUTIONS
Introduction to Automata Theory,
Languages, and Computation
Collected & Prepared By
rontdu@gmail.com
13th Batch (06-07)
Dept. of Computer Science & Engineering
University of Dhaka
Copyright: No copyright
1
TABLE OF CONTENTS
SOLUTIONS FOR CHAPTER

Practice Problems for Final Exam: Solutions
CS 341: Foundations of Computer Science II
Prof. Marvin K. Nakayama
1. Short answers:
(a) Define the following terms and concepts:
i. Union, intersection, set concatenation, Kleene-star, set subtraction, complem

CS 341: Foundations of Computer Science II
Prof. Marvin Nakayama
Homework 11 Solutions
1. Answer each part TRUE or FALSE.
(a) 2n = O(n). TRUE. We can see this by letting c = 2, and noting that 2n
cn = 2n for all n 1. Thus, the definition of big-O holds f

CSE237 - Introduction to the Theory of Computation
January 24, 2002
Problem Set 1 - Solutions
Due January 31, 2002.
1. Prove by induction that for any natural number ,
divisible by 9.
is
Proof:
The proof is in two parts: the basis and the inductive ste

CS 162
Fall 2015
Homework 7 Solutions
November 19, 2015
Timothy Johnson
1. Exercise 9.2.4, pg. 391.
Let L1 , L2 , . . . , Lk be a collection of languages over alphabet such that:
For all i 6= j, Li Lj = ; i.e., no string is in two of the languages.
L1 L

CS 162
Fall 2015
Homework 6 Solutions
November 10, 2015
Timothy Johnson
1. Exercise 8.2.1(b) on page 335 of Hopcroft et al.
Show the IDs of the Turing machine of Figure 8.9 if the input tape contains 000111.
State
q0
q1
q2
q3
q4
0
(q1 , X, R)
(q1 , 0, R)

CS 341: Foundations of Computer Science II
Prof. Marvin Nakayama
Homework 9 Solutions
1. Let B be the set of all infinite sequences over cfw_0, 1. Show that B is uncountable,
using a proof by diagonalization.
Answer: Each element in B is an infinite seque

CS 341: Foundations of Computer Science II
Prof. Marvin Nakayama
Homework 13 Solutions
1. The Set Partition Problem takes as input a set S of numbers. The question is whether
the numbers can be partitioned into two sets A and A = S A such that
X
x=
xA
X
x

Multiplexing, Asynchronous/
Synchronous transmission
Multiplexing
Asynchronous / Synchronous transmission
Synchronous Protocols
9/10/16
1
Multiplexing
9/10/16
2
Multiplexing
Multiplexing means breaking up a higher speed
link into several slower links

W1, L1 - Learning
Outcomes
Introduction
- ice breaker.
Explain data communication theory
Explain why data communication is
important - Information Age
Identify past, present and future data
communication techniques
Demonstrate and explain a basic
com

COSC 4760
Computer Networks
October 27, 2014
Exam 2
Students Name:
ANSWER KEY
This is a closed book examination. The use of notes, texts, or other reference material,
including but not limited to electronic storage, access, or data processing devices is n

COSC 4760
Computer Networks
Homework 4, Network Layer Basics
Due: Monday, Oct 13, 2014, before class.
1. (10 points) You are writing code for part of a network layer stack. You have your IPv4
address. For ease of use, you have it stored as an unsigned int

COSC 4760
Computer Networks
Homework 6, Chapter 5
Due: Friday, November 07, 2014, by 9:00 am
1. (10 points) Give a reasoned discussion, explicit enough that anyone could use it to
create an example, of a two-bit error that a two-dimensional parity check c

COSC 4760
Computer Networks
Homework 1, 8 September 2014
Answers
1. ANSWER:
There is no single right answer to this question. Many protocols would do the trick. Heres a
simple answer below. This assumes that we are using TCP and that, somehow, we are usin

COSC 4760
Computer Networks
Homework 7, Chapter 6
Due: Monday, November 17, 2014, by 11:59 PM (midnight)
NOTE: Copying the answers from some other student OR finding the answers on line and
copying them is cheating. Please, do YOUR OWN WORK!
1. (5 points)

COSC 4760
Computer Networks
Homework 2, Chapter 2 Answers
1. ANSWER: (10 points) Because the user can set up a list of machines that can automatically be logged in from, rlogin can connect WITHOUT a password to any machine
the user has put this list on. T

COSC 4760
Computer Networks
Homework 5, Chapter 4 Finish
Due: Wednesday, October 22, 2014, before class (9:00 AM)
1. (10 points) Compare and contrast link-state and distance-vector routing algorithms.
This does not have to be a long explanation. Please do