Fernando Martin's user avatar
Fernando Martin's user avatar
Fernando Martin's user avatar
Fernando Martin
  • Member for 13 years, 6 months
  • Last seen more than a week ago
  • Buenos Aires, CABA, Argentina
188 votes
28 answers
20k views

Proving the identity $\sum_{k=1}^n {k^3} = \big(\sum_{k=1}^n k\big)^2$ without induction

57 votes
6 answers
18k views

Prove that if $(ab)^i = a^ib^i \forall a,b\in G$ for three consecutive integers $i$ then $G$ is abelian.

47 votes
12 answers
74k views

Proving that the set of limit points of a set is closed

32 votes
3 answers
3k views

Is there a constructive way to exhibit a basis for $\mathbb{R}^\mathbb{N}$?

22 votes
1 answer
615 views

Mathematical suggestions for a long commute

21 votes
4 answers
34k views

Counting the number of paths on a graph

20 votes
2 answers
671 views

Basic categories cheat sheet

15 votes
2 answers
2k views

Motivation for adjoint operators in finite dimensional inner-product-spaces

10 votes
4 answers
3k views

Bijecting a countably infinite set $S$ and its cartesian product $S \times S$

10 votes
4 answers
5k views

What are some alternative definitions of vector addition and scalar multiplication?

8 votes
2 answers
812 views

What fields should I focus on?

8 votes
2 answers
258 views

Proving the convergence of a series

7 votes
1 answer
2k views

Are all continuous everywhere but nowhere differentiable functions fractal in nature?

7 votes
2 answers
371 views

Reference for "a well-known result in finite differences"

6 votes
3 answers
428 views

Do two distinct level sets determine a non-constant complex polynomial?

6 votes
3 answers
523 views

Proving that if a and b are natural numbers, then a!b! | (a+b)!

5 votes
1 answer
368 views

Proving that $||A-B||=||A+B||\Leftrightarrow AB=0$

5 votes
1 answer
1k views

Complex matrices with null trace [duplicate]

5 votes
1 answer
411 views

Motivation for the Sprague-Grundy theorem

4 votes
1 answer
185 views

Dropping some hypotheses on a result involving convergence in distribution

4 votes
1 answer
247 views

Finding all planes that satisfy two conditions

4 votes
1 answer
1k views

The resultant of two homogeneous polynomials is homogeneous

3 votes
0 answers
80 views

The group $\langle a,b | ab=b^2a^2\rangle$

3 votes
0 answers
103 views

An entire function satisfying some constraint must be zero

3 votes
1 answer
426 views

Proving a statement involving the rational root theorem

3 votes
2 answers
366 views

Topics for an undergraduate exposition in number theory

3 votes
1 answer
986 views

Where can I find good resources to practice quadric surfaces and conics?

2 votes
2 answers
425 views

An equality involving limit superior

2 votes
1 answer
747 views

Rings and Categories of Modules by Anderson-Fuller: Exercise 2.2.2

2 votes
1 answer
97 views

Does this argument rely on countable choice?