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Andrews
  • Member for 4 years
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31 votes
Accepted

Find all connected covering space of $\mathbb RP^2\vee \mathbb RP^2$

6 votes

Prove that Christoffel symbols transformation law via the metric tensor

6 votes

$x^p -x-c$ is irreducible over a field of characteristic $p$ if it has no root in the field

2 votes
Accepted

Non-trivial semidirect product $\mathbb Z_3\rtimes Q_8$ is isomorphic to dicyclic group of order $24$

2 votes

When is $A\rtimes_{\phi_1} B \cong A\rtimes_{\phi_2} B$?

2 votes
Accepted

Question about $\operatorname{Aut}(S_6)$ and $\operatorname{Aut}(A_6)$

1 vote
Accepted

Automorphism on subgroup lift to the whole group

1 vote
Accepted

$\text{Aut}(A_6)$ is not split extension of $A_6\cong \text{Inn} A_6$, i.e. $\text{Aut}(A_6) \not \cong A_6 \rtimes ( \mathbb Z_2 \times \mathbb Z_2)$

1 vote

Reference request: representation focused view of quantum mechanics

1 vote
Accepted

Questions on Cartan's magic formula $\mathcal{L}_X=i_X \circ d + d\circ i_X$

1 vote

Hatcher Question 0.27

1 vote

When does Brunn-Minkowski inequatily $(m(A+B))^{1/d} \geqslant (m(A))^{1/d} + (m(B))^{1/d}$ become equality?

1 vote
Accepted

If $I$ is ideal of $R$, $N$ is submodule of $M$, then $I\frac MN=\frac{IM+N}N$

1 vote

A nonsplit short exact sequence of abelian groups with $B \cong A \oplus C$

1 vote
Accepted

Question about "Klein Bottle" in 3 dimension. Algebraic Topology, Hatcher. Exercise 1.2.12.

1 vote
Accepted

Only two different ways to identify three boundary circles of a disc with two holes

1 vote
Accepted

Example of a compact space in $\mathbb R^3$ which is contractible but doesn't deformation retract to any point

1 vote

Existence of homomorphism between middle terms of two exact sequences of abelian groups

1 vote

Derived subgroup of $S_n$ and $D_n$

1 vote

Difference between ramification point and branch point

1 vote

Prove $R_{\mathfrak p}$ has only one maximal ideal $\mathfrak pR_{\mathfrak p}$

0 votes

Hatcher's Algebraic Topology. Exercise 2.2.42

0 votes
Accepted

Understanding Lens space in Hatcher's Algebraic Topology

0 votes

Fundamental group of mapping cone of quotient map from suspension to reduced suspension

0 votes

$f(x)$ is irreducible polynomial on field $k$, $f(\alpha)=0$. $k'$ is field extension of $k$, then $k(\alpha)\otimes_kk'\cong k'[x]/(f(x))$

0 votes

Problem of modules over PID, Exercise $9.13(2)$ in Rotman's Advanced Modern Algebra $2$nd Edition

0 votes
Accepted

In $R$-Mod Category, example for $B\cong A \oplus C \nRightarrow 0 \to A \to B \to C \to0$ splits.

0 votes

$\forall\, 0\to N\to M\to F\to 0 $ exact, $\forall R$-module $E$, $F$ is flat $\implies 0 \to N\otimes E\to M\otimes E\to F\otimes E \to0$ is exact.

0 votes
Accepted

Questions about branch point of holomorphic map

0 votes

Question about $\operatorname{Aut}(D_\infty)\cong D_\infty$