# Learning Abstract Algebra for a graduate degree

I would like to do a graduate degree in mathematics, and I have a full year before I will be able to do so (for personal reasons). I mainly have my weekends available to study.

I am interested in Abstract Algebra in general, I really liked courses like groups, rings, field theory/Galois theory etc'.

I have always found analysis to be difficult for me and courses in the scope of Abstract Algebra felt more natural and intuitive (though I did have some difficulty with some of the more advanced parts of those courses).

I was told that other then taking some credit points I will get a question from the supervisor, one that is not solved yet but seems at a reasonable difficulty to him, and I will have and I will have to try and find a solution for it.

I would like to prepare myself, in this year, to have control over varies subjects in Abstract Algebra so that I will be more likely to be able to solve such a question (or even understand it, as there are some subjects in Abstract Algebra that I have not learned in any of the courses I took as an undergraduate student).

Also, I have lately been aware of some subjects that involve both analysis and Abstract Algebra, such as topological groups.

I would be happy if I could avoid such topics, but I don't know what type of mathematics is studied in a graduate degree level, so this leads me to the following questions:

1. What topics of Abstract Algebra should I study in depth ? what topics in Abstract Algebra should I be familiar with their basics ?

2. Are there any topics in analysis, topology etc' that are likely to be needed for answering a graduate degree level type of questions ?

3. What should be the focus of my work, should I try to do many exercises within the text, or focus on the proofs and the theory ?

I have the book Abstract Algebra by Dummit and Foote to study with, as well as books in other area of mathematics such as Topology by Monkers that might help me with this goal.

I would be extremely grateful for hearing opinions and advices on this matter!

Note 1: I would like to mention that although I try to avoid analysis, I still had to take courses in that, so I don't lack elementary knowledge in many topics, I have taken: Introduction to functional analysis, Real analysis (measure theory), complex analysis, ODE, Introduction to numerical analysis, Introduction to probability theory (the course didn't talk about $\sigma$ algebras and etc' but we did talk about random variables, CLT, etc').

But I don't consider myself to be good at those topics (except maybe probability that I really liked), I understand them, but I am about average at them, so I don't expect that I would be able to do something non-trivial at those topics.

I would like to extend my questions to include the complement of my question to what to study for what I shouldn't spend my time on:

4) Are there topics in Abstract Algebra, or other in other areas that I would need to know (maybe topology ?) that I can skip some parts of (mainly non-core topics that are hard to learn) since they would probably not help me (and due to lack of time) ?

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If you're looking for hints on what to study in your free time to help you with your graduate degree next year, I would seriously consider category theory. It permeates just about everything in topology, algebra and geometry, and in my case it was never formally taught in any course, just mentioned when passing by some special case of a more general result. –  Arthur Oct 18 '13 at 10:44
Avoiding analysis is quite doable in most of algebra. Topology, however, will almost certain turn up somewhere in some form or another. –  Tobias Kildetoft Oct 18 '13 at 10:48
In my humble opinion, any piece of interesting Mathematics will be at the intersection of several subjects. There is no wall between analysis and algebra; please remember that even the virtual walls are there merely for the convenience of organising courses. So, learn as much analysis as you can. Basics of real and complex analysis, functional analysis, measure theory, Fourier analysis and differential equations are important for tools in any mathematician's box. –  kan Oct 18 '13 at 11:06
I tried using D&F for an undergrad math course, and felt that it was too hard. Lang is not easier, far from it, but I think it’s a much better foundation for grad work. If you’ve already used D&F in a course, you can surely hack Lang. –  Lubin Oct 19 '13 at 15:28
If you have a supervisor already, you should ask him/her about that. –  John Oct 23 '13 at 23:37

I will respond directly to this part of your question.

I would be happy if I could avoid such topics [analysis], but I don't know what type of mathematics is studied in a graduate degree level, so this leads me to the following questions:

1. What topics of Abstract Algebra should I study in depth ? what topics in Abstract Algebra should I be familiar with their basics ?

2. Are there any topics in analysis, topology etc' that are likely to be needed for answering a graduate degree level type of questions ?

3. What should be the focus of my work, should I try to do many exercises within the text, or focus on the proofs and the theory ?

4. Are there topics in Abstract Algebra, or other in other areas that I would need to know (maybe topology ?) that I can skip some parts of (mainly non-core topics that are hard to learn) since they would probably not help me (and due to lack of time) ? I have the book Abstract Algebra by Dummit and Foote to study with, as well as books in other area of mathematics such as Topology by Monkers that might help me with this goal.

Firstly, I want to mention that unless you are absolutely certain that you are going to specialize in pure group or ring theory, then you will need some analysis. In fact, you'll probably need a lot of analysis. Explaining why is a bit more complicated. The short version is that almost every area of math relies or is at least informed by analysis, algebra, and topology; this is why most graduate programs (in the US anyway) require these as either graduate classes or graduate entrance exams or graduate qualification tests, etc.

To expand in a slightly longer way - calculus is pretty interesting, and lets you do a lot of things. A common thing that mathematicians do is put measures on weirder spaces so that you can have some variant of integration. In number theory (even algebraic number theory, which is often the same thing as algebraic geometry, which is often the same thing as commutative algebra, which is just algebra and group theory), we really like having measures called Haar measures on matrix groups, like the $GL(n), SL(n), Symp(n)$, etc. This lets us do integration on these groups. So we study functions invariant under actions of these groups, or functions invariant on certain cosets of these groups that behave nicely under ring translation, or some similar idea. And one way we do this is to integrate them, or consider an integral over a weighted average of a function across the cosets our function is invariant over (read: Eisenstein Series for example), to extract largely algebraic information about number fields. Or we consider representations (as in representation theory, which I clump into the larger algebra domain sometimes) and analytic extensions of representations. Everything I've mentioned here requires a certain comfort with topology, analysis, and algebra.

This is to say that algebra mixes quite a bit with analysis in many ways. You would really benefit from having a good understanding of analysis and topology. In particular, don't focus solely on algebra. The other answer says this a little, but I am going to emphasize this a lot. It is very important to understand analysis and topology, unless you are going do limit yourself to pure, remote group theory. And even then, I wouldn't recommend it.

I would prescribe a path into algebra. In a comment on the other answer, you mention that you know groups, ring, fields, Galois theory. Cool! You also say you have Dummit and Foote (by far my preferred introduction to group and ring theory). Then I suggest two paths:

1. Go learn more about whatever parts you liked most. Sylow theorems interest you? Try to learn your way through Burnside's theorem. You like Galois theory? Pick up some infinite-dimensional Galois theory and try your hand. Maybe you already know that? Go pick up some algebraic number theory text - as an intro algebraic number theory text builds nicely on basic field theory and Galois theory, and suggests further paths. To be fair, I'm biased - I'm a number theorist. The important thing is that you go and dig deeper into things that interest you.

2. Pick up Atiyah and MacDonald's Commutative Algebra (hopefully from a library, as they're proud), and do your best at all the exercises. This is the 'natural' extension of what to do next, and it's the real path into a serious interest into algebra in my opinion. I say that you should do all the exercises because this book is famous for having really important lemmas and theorems in the exercises as opposed to the exposition. This will also really set your group theory and ring theory in stone, and you have Dummit and Foote to fall back on if you need. If you know this already, you should next go to Lang's Algebra (quite a bit, scary thing - take a look at it first), Matsumura's Commutative Ring Theory (much, much, much higher than Atiyah MacDonald, even though they have essentially the same name), or Eisenbud's Commutative Algebra (also harder than Atiyah MacDonald, but designed for people interested in algebraic geometry - if you don't know what that is, look it up).

I'd like to add one more thing about your (3) - the problem with learning the proofs and theory is that there is no reason for them to stick on their own. You might open up Atiyah MacDonald and understand everything you read, for example. But I wouldn't expect much of it to last, unless you use it. So a good general philosophy is to read and try to absorb, but then do exercises to let it solidify. Well written exercises require you to build on the text, both as a review and to build intuition.

A hard problem is knowing how many exercises to do. Too many, you waste your time. Too few, you'll forget much. But this is sort of moot, as it's hard to know what problems are useful or good to do before you actually do them, and in some texts some problems are much much better for you than others. For this, I advise you to ask your advisor (or find someone who can provide some sort of guidance) for direction once you have an idea what sort of things you want to learn about.

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Here are my thoughts on your questions - they are, of course, limited by my own knowledge, so take this with a pinch of salt :

1. Groups, Rings and Fields (leading up to Galois theory) form the core of abstract algebra that is taught to almost everyone in graduate school. Depending on your background, I would recommend Herstein's Topics in Algebra. Start with group theory (Lagrange's theorem, Group actions, Sylow's theorems), then do some ring theory (focussing on polynomial rings), and finally start reading about field extensions. Get a solid grounding in group theory though.

2. Don't avoid Analysis and Topology. You might not enjoy it initially, but a lot of interesting mathematics happens when these different worlds collide (for instance, in functional analysis), and not knowing one would prevent you from appreciating this.

3. Focus on problems and examples. Do as many as you can, and use the theorems as black boxes until you have analysed the examples enough to appreciate the proofs. Then go back and learn the proofs (and more importantly, those techniques that show up again and again)

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Thank you for your answer! I have studied all of those topics in (1) as an undergrad student, but I will study them again now in more detail. For (2): I took a functional analysis course (I have edited my question to include what I took), but I don't see my self very good at those topics, they feel a lot more analysis then algebra to me and I am not the brightest student when it comes to analysis.. I will keep (3) in mind –  Belgi Oct 19 '13 at 14:33