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Xiaosong Peng
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6 votes
1 answer
345 views

If two modules are each isomorphic to direct summands of the other, must they be isomorphic?

5 votes
1 answer
308 views

The coherence theorem for monoidal categories

4 votes
1 answer
484 views

The left adjoint of the restriction functor in field extension

4 votes
1 answer
71 views

The tilting module correpsonding to a tilting object of cluster category $\mathcal{C}$

3 votes
0 answers
33 views

When is the group action transitive?

3 votes
1 answer
142 views

A property of functorially finite subcategory

3 votes
1 answer
93 views

The structure of contractible complexes

3 votes
2 answers
63 views

The proof of $S(gh)=S(h)S(g)$ of an antipode in Hopf algebras

3 votes
0 answers
674 views

$\mathbb{Q}/ \mathbb{Z}$ is an injective cogenerator of $\mathbb{Z}-Mod$

3 votes
1 answer
259 views

The relation between quasi-permutation matrix and permutation matrix?

3 votes
0 answers
101 views

Can anyone help me get the following isomorphism of rings?

3 votes
1 answer
260 views

Why it is a distinguished triangle?

3 votes
1 answer
51 views

How to get selfinjective algebras the smallest class of algebras having the following properties?

3 votes
1 answer
47 views

Can we get $f_0,f_1$ uniquely determined by $f$ under the condition $Hom_A(M,Q_0)=0$?

2 votes
1 answer
309 views

Projective injective modules over algebras.

2 votes
1 answer
154 views

Questions on the paper "On the finitistic global dimension conjecture for Artin algebras"

2 votes
1 answer
100 views

Proof explanation of a theorem in the paper "On the finitistic global dimension conjecture for Artin algebras"

2 votes
1 answer
326 views

How to show a bound quiver algebra of a finite, connected and acyclic quiver is a directed algebra?

2 votes
1 answer
75 views

How to prove $Hom_A(P_0,X),Hom_A(P_1,X)$ are injective right $R$-modules?

2 votes
1 answer
359 views

Why are are integrals of functions in coordinates on manifolds not invariant under coordinate transformations?

2 votes
0 answers
41 views

How to show that $Aa/Ja \cong Af/Jf$?

2 votes
0 answers
106 views

An indecomposable $A$-module is also indecomposable as a module of quotient algebra.

2 votes
1 answer
758 views

The simple modules of upper triangular matrix algebras.

2 votes
1 answer
555 views

Are noetherian modules over noetherian ring and artinian modules over artinian ring finitely generated?

2 votes
1 answer
38 views

How to get the following isomorphism $\phi$?

2 votes
0 answers
56 views

A group $G_1$ isomorphic to a subgroup and a quotient group of $G$

2 votes
0 answers
32 views

How to get a Hopf algebra from a monoid?

1 vote
0 answers
175 views

Resultant of multivariate polynomials

1 vote
2 answers
184 views

Could we use Magma to calculate subgroups of a fixed order?

1 vote
1 answer
48 views

Could an equivalence of categories induce the following isomorphisms?