# Finally, More Group Theory

I've just come to the end of the second section of study: Group Theory! It was great to get back to this. Since my introduction to it a few modules ago I had been really curious as to what the next steps were with it all, and it's really fun!

Though now I'm back in the same situation as I was when I was introduced to it: I just want to learn more! Group theory will now be shelved until about March I think (like analysis, there are two group theory sections).

Something I noticed though, even group theory at this level is starting to reflect what Alcock was saying in her book about analysis and the building of theorems to prove another further theorem. As such, I may have benefitted from creating that spider diagram I was such a big fan of before. Next up is linear algebra, but after that is the first section of analysis. I'll have to go into that with the view to actually making that spider diagram to get an overview of how all the concepts build on each other.

# Feedback - 01

I received the marks back for my first monster assignment! Did quite well as it turns out! But this blog isn't about spouting about my success, it's about the learning process! So here's some of the things I screwed up...

First off, my algebra is clearly rusty as fuck. In one instance put a minus sign in the wrong place AND mysteriously lost a factor of 2 in the progress of my working. In future I really need to re-read my working really carefully (three or four times over it seems), both the hand-written and the full typed-up LaTeX...

Something else I lost marks for was the apparently simple task of graph sketching, either where I hadn't considered asymptotes or had not considered the limits of the domain. Overall I clearly need to be a lot more mindful of whether I'm dealing with $\leq$ or $<$. When I read those symbols I see them both so often, I frequently gloss over them without properly considering their usage. Again, pretty basic stuff.

With complex numbers I apparently need to be more explicit with my declaration of forms. My polar form was implicit in the answer, but there wasn't anywhere I actually stated it. Silly boy.

I fell down on a proof of symmetry for an equivalence relation. I just wasn't mindful whilst answering this. It is assumed that $x-3y=4n$. This can be rearranged in terms of $y$ as $y=\frac{x}{3}-\frac{4n}{3}$. So substituting y, in the symmetrical $y-3x$ results in: $4 \left(-\frac{2x}{3}-\frac{2n}{3}\right)$. Of course, at this point, proving that what's inside the brackets is an integer is pretty difficult. But that's where I left it. A bit more play would've shown that I could easily have arranged the first equation in terms of $x$ instead which would've resulted in $4\left( -2y-3k\right)$, which is rather obviously an integer given the initial variables. More exploration required in future...

Lastly, in my last post I mentioned how there was a distinct lack of symbolic existential or universal quantifiers in all this new material. After Velleman, I was so used to seeing them, and working with them appropriately but because they're now not around, I got totally burnt by assuming I had to prove "there exists" instead of "for all" for one question. I suppose I'll be able to get around this with making sure my notes explicitly state whatever quantifier we're actually talking about. Damned English language... Symbols are much more concise! 🙂