17500-30 Elementary Number Theory

Fall 2006


Instructor

Anna Wienhard

Email

standard email

Reader

Lola Thompson, lola@uchicago.edu





Office hours

Ry360I, Mondays 10:00-11:30 and Wednesdays 17:00-18:00.



Course info

Lectures TThu 10:30 - 11:50, E207


Book

An Introduction to the Theory of Numbers by Niven, Zuckerman and Montgomery

Exams

Hour Test: Thursday, October 26 (in class) Review topics
Final: Tuesday, December 5, 10:30 - 12:30 in E207 Review topics





General Policy: Homework will be assigned weekly. There will be a one hour test in class and one final exam.

Let me just recall the homework policies. You are encouraged to work on homework together, but you must write up the solutions by yourself. Please indicate with whom you worked together. If you stumble across the solution to a homework problem in a book or somewhere else, you may write up this solution, but you have to give the reference where you got it from. No late homework will be accepted. Please order and staple your solutions together and put your name on it. Unreadable homework will not be corrected.

Grading: 

·  Homework: 30%

·  Hour Test: 30%

·  Final: 40%


Home work: Homework is due at the beginning of class. Exercises are from Niven, Zuckermann, Montgomery: An Introduction to the Theory of Numbers, Fifth Edition, unless specified otherwise.

Due

Homework Assignment

03 Oct 06

Solve Problems 1 (a), 3 (a) (b), 6, 7 on page 17, Problems 20, 23 on page 18, Problems 4, 6, 7 on page 29 and Problems 24, 25 on page 30. Bonus problems: Problem 13 on page 17, Problems 44 and 45 on page 19, Problem 17 on page 29 and show that there are infinitely many primes of the form 6x-1.

10 Oct 06

1) Problems 2,3 5 on p. 56; 16 on p.57; 35 on p.58; 54 on p.59
2) Problem 4 on p.62, Problem 5 (a), (c), (e) on p. 63
3) Let m be a positive integer, m>1. We denote by Z/mZ the set of equivalence classes of integers modulo m. a) Show that Z/mZ is a ring. b) Show that Z/mZ is a field if and only if $m$ is prime. (If you do not know the defintion of a ring or a field, consult Definition 2.12, p.124 and Definition 2.9, p.116)
Bonus: Problem 38 on p. 58. Problem 24 on p. 73, Problem 44 on p. 74.

17 Oct 06

1) Problem 4 on p.72: Find all integers which satisfy the following congruences simultaneously: x=1(mod 3), x=2(mod 4), x=3(mod 5)
2) Problem 10 on p.57
3) Problems 16 and 22 on p. 57
4) Problem 2 on p.82
5) Problem 1 on p.86
Bonus: Prove that any odd integer n>1 is prime if and only if it is not expressible as a sum of 3 or more consecutive positive integers.
Problem 5 on p. 86.

24 Oct 06

1) Problem 1 on p.62, Problem 8 on p.63
2) Problem 15 on p.72, Problem 6, 7 on p.91
3) Problem 10 on p.91
4) Let p>2 be a prime number. Let a/b with a,b relatively prime be the fraction obtained as a/b =1+ 1/2 + 1/3 + ... + 1/(p-1). Show that p divides a.
Bonus: Problem 11 and Problem 12 on p. 63

31 Oct 06

Review material for the midterm
1) Problem 1, 2, 3 on p. 96
2) Problem 1, 5, 7, 13 on p. 106
3) Find a prime p such that 2,3 and 5 are primitive roots modulo p.


07 Nov 06

1) Go through your midterm and think again about the problems you did not solve correctly.
2) Euler's Function: Problem 28, 30, 32, 33, 35 on p. 73
3) Primitive Roots: Problem 2,3,4 on p. 106, Problem 18 on p. 107 (Note that the book sometimes says that a belongs to the exponents h modulo m, which means the same as saying that a is of order h modulo m.)
Bonus: Problem 29 on p. 107


14 Nov 06

1) Problem 22 on p. 107
2) Problem 3,4,7, 9,11 on p. 135/136
3) Problem 1,4 on p. 140
4) Problem 8,11 on p. 141
Bonus: Problem 21, 23 on p. 137


21 Nov 06

1) Problem 2,5 on p. 147, Problem 15 on p. 148.
2) Write down the Farey sequence (between 0 and 1) of order 6 and 7.
3) Problem 1,2,3 page 300, Problem 5 on p. 301.
4) Problem 1, 6 on page 307.
Bonus: Problem 9 on p. 301.


28 Nov 06

1) Problem 1, 3, 4 on p. 327.
2) Problem 2, 3, 4 on p. 333, Problem 1, 2 on p. 336.
3) Problem 2 on p. 344 (you can use Farey fractions or continued fractions to solve this)
Bonus: Problem 6 on p. 341


Practice Final

Practice Final

 

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