goblin GONE's user avatar
goblin GONE's user avatar
goblin GONE's user avatar
goblin GONE
  • Member for 11 years, 5 months
  • Last seen more than 3 years ago
181 votes
14 answers
13k views

How do you revise material that you already half-know, without getting bored and demotivated?

118 votes
2 answers
123k views

Determinant of a non-square matrix

54 votes
2 answers
2k views

Is Pythagoras the only relation to hold between $\cos$ and $\sin$?

48 votes
3 answers
5k views

I don't get the relationship between differentials, differential forms, and exterior derivatives.

46 votes
7 answers
2k views

Struggling with "technique-based" mathematics, can people relate to this? And what, if anything, can be done about it?

39 votes
4 answers
18k views

Cross product in higher dimensions

36 votes
5 answers
2k views

Is $\mathbb{N}$ impossible to pin down?

34 votes
0 answers
563 views

Smallest Subset of $\mathbb{R}_{>0}$ Closed under Typical Operations

31 votes
2 answers
2k views

Is second order logic even a logic?

25 votes
4 answers
2k views

How can we think and/or write rigorously about integration by substitution?

24 votes
3 answers
3k views

What's the point of modal logic?

21 votes
3 answers
2k views

What is dual to "There exists unique?"

21 votes
6 answers
2k views

Why hasn't GCH become a standard axiom of ZFC?

21 votes
6 answers
2k views

What problems, ideas or questions first got you interested in algebraic geometry?

20 votes
3 answers
1k views

Is there an axiomatic approach to ordinal arithmetic?

19 votes
3 answers
7k views

Do people ever study non-commutative fields?

19 votes
1 answer
573 views

Is $\mathbb{Z}$ the only totally-ordered PID that is "special"?

18 votes
4 answers
10k views

Traveling salesman problem: why visit each city only once?

17 votes
2 answers
3k views

How does (ZFC-Infinity+"There is no infinite set") compare with PA?

17 votes
3 answers
616 views

Looking for an approach to mathematical notation wherein the universe is divided into disjoint worlds.

17 votes
1 answer
803 views

Non-associative version of a group satisfying these identities: $(xy)y^{-1}=y^{-1}(yx)=x$

17 votes
5 answers
8k views

Are derivatives defined at boundaries?

16 votes
3 answers
4k views

Why are addition and multiplication included in the signature of first-order Peano arithmetic?

16 votes
1 answer
4k views

Is there a general theory of the "improper" Lebesgue integral?

15 votes
0 answers
249 views

Is there a finite list of identites in the language of $(\mathbb{N},0,1,+,\times,\mathrm{gcd},\mathrm{lcm})$ that generates all the others?

15 votes
1 answer
973 views

What are the commutative quasigroups satisfying $a/b=b/a$?

15 votes
6 answers
1k views

Should every group be a monoid, or should no group be a monoid?

15 votes
3 answers
1k views

When we say, "ZFC can found most of mathematics," what do we really mean?

14 votes
2 answers
4k views

Do there exist functions satisfying $f(x+y)=f(x)+f(y)$ that aren't linear?

14 votes
5 answers
666 views

Can an algebraic structure have indistinguishable elements?

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