For those who are interested, you can read my previous post.
I began self studying real analysis around 2 weeks ago. I've chosen to follow Stephen Abbott's Understanding Analysis based on the comments I read on Amazon.
I have gone through the first chapter, including all the exercises. It covers sets, functions, real numbers, completeness, cardinality and Cantor's Theorem. This is my first time studying real analysis so I have no other books to compare to. But in my opinion, this is an excellent text for self study. I especially like the author's writing and organization. He spends quite some time talking about the motivations behind real analysis and why mathematicians invented it. The proofs were well written, and tend to be on the verbose side of things, but I think it's excellent for first time learners. The exercises reinforce what's being learned and shouldn't be skipped. They force me to think deeper about the material. I also find the epilogue very interesting as it gives readers extra information as well as some historical background regarding the materials covered in the first chapter.
It's only one chapter, but I already feel like it would be a long struggle. Calculus was my strong area when I was in secondary school but this is on another level. Well, technically real analysis NOT calculus! Nothing is intuitive. Definitions and theorems need be read 3-4 times in order to grasp what's being said. All the proofs are like magic. I honestly think that even if I time travelled back to my college days, I would not be spending less effort just because I was younger. So far, I find the Schroder-Bernstein Theorem most impressive and beautiful. I am surprised that its proof is left as an exercise to the reader. It deserves to be fully presented.
I've been using DeepSeek as a studying aid so far. I'm using the free version and I always turn on "expert mode." I don't know the difference between expert mode and think mode and what happens if I turn on both. DeepSeek says they're the same but judging from the output I'm not so sure. Here's how I've been using it.
- Verify my answers to the exercises
- Ask for hints and directions when I'm stuck in the exercises
- Ask for simpler explanations, analogies, and concrete examples to build an intuitive understanding of theorems or definitions
- Ask general questions as if it's a real TA (teaching assistant)
Here are my initial thoughts.
- One word: INDISPENSABLE. I don't think I would have survived even the first chapter without AI's help.
- In particular, as I mentioned above, Schroder-Bernstein Theorem was left as an exercise to the reader. Had DeepSeek not given me a concrete example, I would have never grasped the underlying idea, let alone proving it.
- I was saved a number of times by AI when I was really stuck in the exercises. The hints either confirmed that I was thinking in the right direction and motivated me to continue, or gave me a kick in finishing a key step of a proof.
- This is specific to DeepSeek. I cannot just take a photo/screenshot of an exercise and ask it to read the question for me. I had to type it in. It's tedious for things like subscripts and set operators. Especially with the latter, I had to describe them in words like "A is a subset of B intersect C."
- On the other hand, I was quite surprised that DeepSeek was able to understand what I wrote ALL THE TIME, like a(n) was immediately recognized as "a sub n"; R, N, Q were immediately understood as set of real numbers, natural numbers and rational numbers respectively. At one point, I needed to explain my solution by describing a binary tree with only words. Nevertheless, it was able to grasp my idea correctly and draw that tree out for me. Sometimes I was afraid it might not understand what I said, like "infinite union of A(n)", but so far it never failed to understand me.
- It had small misses but they're relatively easy to spot.
- There were one or two big misses though, like when it thought a certain mapping is onto but actually not. In both cases, I just asked "Are you sure?" and it was able to recover from its mistakes.
- It felt good when it praised the answers I gave or even when I asked questions 😆 For example, "This is a fantastic observation", "Your solution is more elegant than the standard approach." etc.
- This is specific to DeepSeek: It couldn't graph functions in-place. It just gave me python code to run. On the other hand, both Gemini and ChatGPT can do that.
- This is also DeepSeek specific. I don't understand the difference between Expert mode vs toggling the "Think" button. I asked DeepSeek to explain itself and it said they're the same. But by toggling on the "Think" button, I can see how DeepSeek is thinking. Expert mode does not show how it thinks. So, I'm not sure if they're really the same.