Instructor: Timothy Riley
Lectures
Tuesdays & Thursdays
11:40am–12:55pm
in MLT 224
Office hours
Mondays
2pm–4pm (t.b.c.)
in MLT 403
MATH 3560 is a geometric introduction to the algebraic theory of groups, through the study of symmetries of planar patterns and 3–dimensional regular polyhedra. Besides studying these algebraic and geometric objects themselves, the course also provides an introduction to abstract mathematical thinking and mathematical proofs, serving as a bridge to the more advanced 4000–level courses. Abstract concepts covered include: axioms for groups; subgroups and quotient groups; isomorphisms and homomorphisms; conjugacy; group actions, orbits, and stabilizers. These are all illustrated concretely through the visual medium of geometry.
MATH 3560 is a 4–credit course. The course catalogue states that the prerequisite is at least one of
MATH 2210 — Linear Algebra
MATH 2230 — Theoretical Linear Algebra and Calculus
MATH 2310 — Linear Algebra with Applications
MATH 2940 — Linear Algebra for Engineers.
If you have not satisfied the prerequisite, seek permission of the instructor to take the course. Prior knowledge of group theory is not a prerequisite.
Grades will be computed according to:
Prelim
15%
Essay
15%
Presentation
5%
Final exam
35%
Homework
30%.
Cornell's code of academic integrity applies to this and all other courses. In particular, academic misconduct of any kind may result in a grade penalty or the assignment of a failing grade.
Prelim
In class, 8th October 2013, covering Chapters 1–8
The exam (scored out of 40), Solutions, Mean: 29.2, Median: 28.3, Standard deviation: 4.6
Final
7:00pm–9:30pm, Wednesday 18th December 2013, RCK110, comprehensive
Exams will be taken without the aid of any textbooks or notes.
Calculators will NOT be allowed for the exams. Cell phones, MP3 players and other electronic devices (aside from watches) will NOT be allowed in the exam room, not even as time–keeping devices.
Accommodations may be made in the event of illness, a clash with another examinations, a conflict with religious observances, or other serious circumstances — please contact your instructor as early as possible. Students who miss exams and then present excuses that could have been given in advance will not be looked upon favorably. Do not make travel plans that conflict with the exams.
If you have been approved for extended–time or special–condition exams by Cornell Student Disability Services, notify your instructor in the first two weeks of the semester.
Due 9/3:
Make a tetrahedron.
1.3, 1.4, 1.9
Due 9/10:
Draw the Cayley diagram (a.k.a. Cayley graph) for the rotational symmetries of the tetrahedron with respect to the rotations r and s of Ex. 1.3 and 1.4.
2.2, 2.3, 2.8, 3.5, 3.9, 3.10
Due 9/17:
4.2, 4.5, 4.8, 5.3, 5.8, 5.9
Due 9/24:
6.1, 6.2, 6.4, 6.9, 6.11, 6.12
Draw the Cayley diagram for S4 with respect to (1 2 3 4) and (1 2).
Due 10/1:
Make a cube or octahedron, and a dodecahedron or icosahedron. (A prize for the best!)
What do you get if you join up the midpoints of adjacent faces of a tetrahedron? What if, instead, you join up the midpoints of adjacent edges?
7.1, 7.3, 7.6, 8.1, 8.4
10/8:
No homework (prelim)
Due 10/17 (note day):
9.1, 9.5, 9.7, 9.12, 10.6, 10.7, 10.11
Due 10/22:
11.1, 11.2, 11.3, 11.4, 11.8
Due 10/29:
12.2, 12.3, 12.7, 12.8, 12.12 (read Example vi in Chapter 12), 13.2, 13.4
Due 11/5:
14.1, 14.4, 14.5, 14.6, 14.11, 15.3, 15.6, 15.12
11/12:
Please work on your essays! Hand in a one-page essay plan (not for credit).
Due 11/19:
16.1, 16.7, 16.8, 16.10, 17.2, 17.3, 17.9 (C was defined in Chapter 3), 17.10
11/26:
No homework (essays due)
Due 11/3:
18.2, 18.3, 18.5, 19.2, 19.3, 19.4, 19.7
Solutions. Follow this link to TA's page for solutions and statistics.
Practical information. MATH 3560 is a four–credit course, so you should plan on spending at least twelve hours a week working on it. Homework is the most important part of MATH 3560 since mathematics is really learnt by doing it.
Homework assignments will be due in class on Tuesdays. Papers should be stapled and your name clearly indicated. Late homework will not be accepted. If you have a medical excuse or other serious circumstances, allowences will be made; contact your instructor at the earliest opportunity. The lowest score across the semester will be dropped (as everyone has a bad week sometime).
I expect homework to be graded and returned within a week. Due to constraints on resources, not all problems may be graded.
Collaborating. You may collaborate with other students on homework. I believe, however, that for maximum benefit, you should try hard to do all the problems yourself before consulting others. What you turn in should represent your own solutions expressed in your own words, even if you arrived at these solutions with others. Remember, you are doing the homework to learn the material; do not try to defeat its purpose. Copying someone else's homework and presenting it as your own will be treated as a violation of Cornell's Academic Integrity Code, as will copying solutions that you might find on the internet or elsewhere.
In keeping with the good practice of acknowledging all contributors to a piece of work, if you do collaborate, please give the names of your collaborators so on your homework. (Your grade will not be affected.)
Students agree that by taking this course all required papers may be subject to submission for textual similarity review to Turnitin.com for the detection of plagiarism. All submitted papers will be included as source documents in the Turnitin.com reference database solely for the purpose of detecting plagiarism of such papers. Use of the Turnitin.com service is subject to the Usage Policy posted on the Turnitin.com site.
Writing well. Mathematics is not mere computation; arguments and abstract concepts must be communicated. Use complete sentences with proper spelling, grammar, and punctuation. Write linearly down the page rather than scattering words, symbols and equations around. Explain your reasoning carefully. Indicate the significances of and relationships between any calculations which contribute to your answers. Define and employ clear and concise notation. State clearly any results (from lectures or from the textbook) to which you appeal in your solutions. Imagine your fellow-students as your readers — ask yourself whether they would they be able to follow your arguments.
If you would like to try using LaTeX for typing up your homework (to quote the above document "it beats the pants off Word"), here's a guide to getting started. Whilst LaTeX produces beautiful results and is a good skill to have, it'll take a lot of work at first. Well hand-written homework is fine instead.
Support. The Mathematics Support Center in Malott 256 provides free tutoring. Details of my office hours and those of the T.A. are on the course homepage.
An essay will be due in class on 11/26. There may also be a short associated presentation in class towards the end of the semester.
Here are suggestions for topics.
Möbius transformations: the symmetries of the hyperbolic plane
Group theory on the Cornell campus. This one might take some imagination! Search for and write about group theory on the Cornell campus (e.g. in the architecture, in the flora, or in any other setting you can find).
Group theory and spectroscopy. This article might be a good starting point.
Group theory and crystallography. Wikipedia is a good start.
The Lovász Conjecture. This concerns paths in Cayley graphs.
Growth in groups. See Groups, Graphs and Trees by John Meier, for example.
The lamplighter group. See Groups, Graphs and Trees by John Meier, for example.
The history of group theory: how did the modern concept of a group emerge? The wikipedia page on group theory is a reasonable start.
Group theory in music. See David Benson's Music: a mathematical offering, for example.
Enumerating isomers using group theory. Kennedy, McQuarrie, Brubaker
The Word Problem for groups. See Groups, Graphs and Trees by John Meier, for example.
Group theory and Klein's Erlangen Program
Alternatively, you are welcome to come up with your own topic. Explaining links between group theory and other academic areas of interest to you, would be particularly welcome. Two provisos are that you may not duplicate work you have done elsewhere and there must be some genuine group theory involved.
To gauge the appropriate level and style, imagine you are writing for your classmates. Explain why your topic is interesting and important, and convey the main ideas. Some subjects will allow you to go into the details of the mathematics. Others lend themselves better to a more journalistic approach, as the mathematics may be too technical or too substantial. Whatever style you choose, try to include at least some mathematical detail.
Please aim for about 2500 words.
Please take care over your presentation and try to make your writing fluent and compelling. I do not insist you type your essays, but I do recommend it. LaTeX and its variants can produce beautifully typeset mathematics, but other software is also viable.
Cornell's Academic Integrity Code states that a Cornell student's submission of work for academic credit indicates that the work is the student's own. All outside assistance should be acknowledged, and the student's academic position truthfully reported at all times. Please include a full bibliography of articles, books, web sites etc. Any text lifted from a source should be presented as a quotation. If you base some exposition on someone else's writing, you should acknowledge the source. You may not collaborate on these essays.
Students agree that by taking this course all required papers may be subject to submission for textual similarity review to Turnitin.com for the detection of plagiarism. All submitted papers will be included as source documents in the Turnitin.com reference database solely for the purpose of detecting plagiarism of such papers. Use of the Turnitin.com service is subject to the Usage Policy posted on the Turnitin.com site.
Timetable for presentations
21 November
Zachary
Group theory in crystallography
Christine
Group theory in physics
Han
Enumerating isomers
Daqian
Lie groups
26 November
Peter
The Lovász Conjecture
Mike
The Lovász Conjecture
Andrew N.
Music and group theory
Kelvin
Music and group theory
3 December
Rose
Braid groups
Katherine
Braid groups
Colleen
Rubik's cube groups
Andrew C.
Group theory and cryptography
5 December
Pra
Galois theory
James
The Banach–Tarski Paradox
Will
History of group theory
Lisa
Burnside's Problem
Some guidance on giving presentations
— Our classes are 75 minutes long. We will devote four classes to these presentations, four per class. Please prepare a 15 minute talk, leaving a few minutes for questions and for completing a brief feedback form.
— In the instances where two of you are speaking on the same topic, please collaborate in making a 30 minute presentation, with each of you presenting for 15 minutes. Decide who will go first and how to divide up the material.
— Fifteen minutes is a short amount of time for a technical presentation. Do not try to say too much. (When presenting mathematics for the first time in front of an audience, it is a common mistake to prepare about three times as much material as you have time for.) You only really have time to make one main point. So choose one thing to communicate, rather than trying to convey the entirety of your essay. You are unlikely to have time for a detailed proof of anything.
— The aim of your talk should not be to convince me that you have understood a lot of mathematics. Rather, your aim should be to communicate some interesting mathematics to your classmates.
— You might be wise to deliver a practice run-through of your talk to a friend. Or you could pair off with a classmate and practice.
— Please attend everyone else's talks. These talks are a continuation of the course: subjects we have learnt about will be developed further, and new important topics will be introduced. I hope you will support and encourage each other, and learn about different ways of giving talks from each other's example.
— I am available to advise you on the content of your talk. Please come to office hours or e-mail me to make an appointment.
— Please feel free (encouraged even) to ask questions in each other's talks.
— Please acknowledge your sources.
— Please think about how you will present your talk. Write clearly on the blackboard. We will not have time to set up projectors for computers or for transparencies. Some of the topics may benefit from pictures, but these may be too time–consuming to draw on the spot in class, so you might like to prepare handouts.