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Joppy
  • Member for 5 years, 4 months
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99 votes
6 answers
33k views

The Langlands program for beginners

  • 1,845
55 votes
3 answers
2k views

Proving $\left(1-\frac13+\frac15-\frac17+\cdots\right)^2=\frac38\left(\frac1{1^2}+\frac1{2^2}+\frac1{3^2}+\frac1{4^2}+\cdots\right)$

37 votes
3 answers
3k views

If $(A-B)^2=AB$, prove that $\det(AB-BA)=0$.

  • 2,066
34 votes
6 answers
2k views

Proof that $\text{det}(AB) = \text{det}(A)\text{det}(B)$ without explicit expression for $\text{det}$

  • 1,076
13 votes
1 answer
605 views

given the inverse of a matrix, is there an efficient way to find the determinant?

12 votes
1 answer
296 views

What is the fundamental group of the variety of singular matrices, without $0$?

  • 19.7k
12 votes
3 answers
402 views

Help me prove $\pi^{e}<23<e^{\pi}$.

11 votes
4 answers
956 views

Prove $\rm AB = BA = 0$ if the set of nonzero eigenvalues of $\rm A + B$ is union of set of nonzero eigenvalues of $\rm A$ and $\rm B$.

  • 1,055
8 votes
1 answer
121 views

On a function from a group with values lying in an inner product space

7 votes
1 answer
190 views

R integral domain, Q its field of fraction, M R-module with nontrivial annihilator. Is Ext(Q,M) always 0? [duplicate]

7 votes
0 answers
1k views

Closed Form for this Taylor Series?

7 votes
2 answers
194 views

Group Isomorphic to $(\mathbb{Z} \times \mathbb{Z})/ \langle(a,b),(c,d)\rangle$

6 votes
1 answer
455 views

On the existence of limits of multivariable rational functions

5 votes
1 answer
179 views

Differential operators as a quantization of functions on the cotangent bundle

4 votes
1 answer
158 views

Is the product of two Zariski closed subgroups of $GL_n$ still Zariski closed?

  • 19.7k
3 votes
1 answer
568 views

Lift of symplectic form to the cotangent bundle

3 votes
0 answers
52 views

Ideals generated by polynomials of the form $X_iY_j$ and $X_iY_j-Y_iX_j$ are radical?

3 votes
1 answer
117 views

A matrix is the unit matrix iff any equation of the form $X^{k}=A$ has at least one solution.

2 votes
0 answers
178 views

Invariants in the ring of coinvariants

2 votes
1 answer
100 views

$(M, \cdot)$ monoid, $A \subset M, \forall x \in M, \exists k \geq 1$ such that $x^k \in A$

  • 3,574
1 vote
0 answers
39 views

strong independence of simple representations over algebraically closed field

  • 12.8k
1 vote
0 answers
297 views

Tangent space of a scheme of finite type over a field

  • 31.1k
1 vote
0 answers
99 views

Motivating the definition of a morphism between varieties

  • 1,614
0 votes
1 answer
94 views

Recovering tree structure from pairwise distances

  • 53