Instructor: Alice Medvedev

Office: 6278 NAC

Office Hours: Thursday 6 - 7 pm, Tuesday 12:30pm-1:30pm, or by appointment.

E-mail: amedvedev at ccny

- Problem Set 0, due at 2pm on Tuesday, September 2nd. ps0.tex
- Problem Set 1, due at 2pm on Tuesday, September 9th. ps1.tex
- Problem Set 2, due at 2pm on Tuesday, September 16th: do exercises 2.9-2.12, 2.19 from Dym; read Blecksmith's notes on equivalence relations, decide which of examples 5-24 are equivalence relations, and do the exercise on the bottom of p.3 there.
- Problem Set 3, due at 2pm on Tuesday, September 30th. ps3.tex
- Problem Set 4, due at 2pm on Tuesday, October 7th. ps4.tex
- Problem Set 5, due at 2pm on Tuesday, October 14th. ps5.tex
- No problem set due October 21st - study for the full-size in-class midterm!
- Problem Set 6, due at 2pm on Tuesday, October 28th. ps6.tex
- Problem Set 7, due at 2pm on Tuesday, November 4th. ps7.tex
- Problem Set 8, due at 2pm on Tuesday, November 11th. ps8.tex
- Problem Set 9, due at 2pm on Tuesday, November 18th. ps9.tex
- Problem Set 10, due at 2pm on Tuesday, December 2nd. ps10.tex
- Notes for the example worked in class Tuesday, November 25th.
- Problem Set 11, due at 2pm on Thursday, December 11th. ps11.tex

I also encourage you to use LaTeX to typeset your homework solutions. Latex is used to typeset anything with formulas by almost all scientists and some engineers, so it is worth learning whether or not you intend to become a mathematician. It is fairly easy to learn by example, and less easy to learn from books and tutorials, so I will post the source-code (.tex files) for my homeworks for you to use. If you do not want to install anything on your computer, there are many online-compiling options.

The sum of all the homework grades and the sum of the three exam grades (20% mini-midterm, 35% full-size midterm, and 45% final exam) will have equal weight in determining your course grade. The raw homework and exam grades are not percentages to be converted into letter-grades as in high-school! If you are not sure how you are doing in the course, talk to me.

If you have not had much experience with abstract mathematics, Introduction to math notation by George M. Bergman will help. You also want to make friends with equivalence relations (for example, here or here) and with basic naive set theory.

The text for this course is

We will cover Chapters 1 and 2 fairly quickly: hopefully, most of you have seen much of this material in previous courses. By the end of the semester, I expect to cover chapters 1-6 thoroughly, and touch on some topics in later chapters. If there is some topic you would particularly like to see, let me know by the end of September, and I will try to get to it by the end of the course.

- Proofs are made of complete, grammatically correct sentences.
- All variables that appear in the proof either appear in the statement being proved, or are clearly introduced somewhere in the proof with a "let".
- Each statement either clearly, logically follows from previous statements (and that logic is explained), or is introduced with an explicit purpose (e.g. "suppose towards contradiction that..." or "the inductive hypothesis is...")
- Anything that is not proved is cited, by its common name (e.g. the Fundamental Theorem of Arithmetic) or by reference to our textbook (e.g. Proposition 4 on p. 10) or to another source.

It is reasonable to expect emails to be answered within a day or two; it is unreasonable to expect an answer within an hour. The truly urgent questions (where's the final exam - i'm already late?) are better answered by google or a phone call to the relevant university office. Some questions that feel urgent (did I pass the class?) simply require patience.

Email is great for logistics: finding a time to talk outside regular office hours, making special arrangements for missed work, telling me about a problem with the web page or a homework, etc. Email does not work well for discussing mathematics - come to my office hours instead.

If a professor (or, really anyone else!) agrees to meet with you personally, outside of lecture and standard office hours, and then you find out that you will not make it to the meeting, you should inform the professor of this at least several hours in advance.

You are also responsible for your learning, from knowing what material has been covered to making sure you understand that material. The lectures will not cover everything; the problem sets will not cover everything; the textbook is the closest to covering everything. You will certainly have to learn some things on your own, either from the textbook or really on your own. Some of the material this course covers is genuinely difficult: you will probably not get it on the first try; that's ok. To maximize the number of tries, read the textbook before the lecture, noting the parts you don't understand; then come to lecture and pay special attention to those parts and ask lots of questions; then read through the book again and you will discover new subtleties you don't quite get. Come to office hours to clear up those, work on the homework, come to more office hours, read comments on graded homework, and read through the text one more time. By this point, two or three weeks after meeting the concept for the first time, you should be comfortable with it. The bottom line is, your job is to acquire knowledge, not simply to follow my instructions. This course is graded on accomplishment, not effort.

The best use of lecture is to focus all of your attention on it, for the entire duration. If you are not doing this, please do not disturb the people who do. If you come late or leave early, sit near the door and don't let the door slam. If you're eating, please don't be loud or smelly (if you bring hot pizza, bring enough for everyone!). Whether or not you're playing with your cell phone, make sure it's silent.

The best way to stay focused in class is to get involved. If something doesn't quite make sense, ask about it! I like questions! I like stupid questions, too - for every brave soul willing to ask one, there's ten shy confused students thinking the same thing. If you think there's a typo on the board, you may well be right - ask about it! Sometimes, I'll make them on purpose, to keep you on your toes. Other times, I'll make honest mistakes - I'm not perfect. And if it's not a typo, your confusion will not get cleared up if you don't ask. Clearing up confusions is what this is all about.

So, what do you do with a confusing definition or theorem or proof? First, you make sure you understand each word and symbol that appears in it. The "appear in" partial order is well-founded, so induction works. Then you try to think of explicit examples. For a definition, look for things that satisfy it, as well as for things that don't. For a theorem, look for an example that satisfies the hypothesis and see that it satisfies the conclusion, and then for some examples that don't satisfy the conclusion and see which hypotheses they fail. Similarly, to understand a proof, it is often helpful to go through it with a specific example in hand; a non-example that fails some of the hypotheses will make it easier to see where the proof needs those hypotheses, i.e. breaks without them. The best way to understand a proof is to completely forget it and then try to prove the result yourself; this is also the slowest way. The next step is to ask why this particular definition was chosen, or why the theorem was stated in this particular way. Varying a definition, you may find equivalent definitions, stupid definitions, or new interesting concepts. Varying a theorem, you will find many false statements, some true generalizations, and occasionally an entirely new result. This is what us mathematicians do when we aren't teaching.

Appropriate academic accommodations are offered to students with disabilities.

The university's policy on academic integrity.