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Linear representations of algebras and groups, Lie theory, associative algebras, multilinear algebra.

4 votes
Accepted

Is this a counterexample to Reineke's conjecture on total stability conditions for Dynkin ty...

Your argument looks correct to me. Note that the corresponding question for the derived category has been answered positively, and a parameterisation of total stability conditions given by QiuYu and Z …
Matthew Pressland's user avatar
12 votes

Classification of finite type structures leads to Dynkin diagrams?

You may be interested in the classification of quivers of finite mutation-type: http://www.emis.ams.org/journals/EJC/Volume_15/PDF/v15i1r139.pdf This extends the classification of mutation classes of …
3 votes

In quiver rep,is it$\mathrm{Ext}^i_{\mathrm{rep}}(\mathcal{X},\mathcal{R})=0 ‎\leftrightarro...

This statement is false. Take $R=k$ a field, and $\mathcal{X}$ any finite-dimensional representation of $\mathcal{Q}$ over $k$. Then for $i>0$ and $v\in\mathcal{Q}_0$, there is some $n\geq0$ such that …
Matthew Pressland's user avatar
3 votes
Accepted

Weakly symmetric Frobenius algebras

Yes. Using left modules, the indecomposable projective $eAe$-modules are $eP$ for $P$ an indecomposable projective $A$-module such that $e\operatorname{top}(P)=\operatorname{top}(P)$, and in this case …
Matthew Pressland's user avatar
1 vote

$\mathrm{Ext}$ group in representation theory

This is true when $R$ is a field (or semisimple, so a product of fields), for the following reason. Since $v_1$ is a source, there is a monomorphism $\mathcal{X}'\to\mathcal{X}$, which fits into a sh …
Matthew Pressland's user avatar
4 votes
Accepted

Gaps in the projective dimensions of simple modules

For $n>0$, let $A_n=KQ_n/I_n$ as follows: $Q_n$ is the quiver with vertex set $\{1,2\}$ and arrows $\alpha_i\colon 1\to 2$ and $\beta_i\colon 2\to 1$ for $1\leq i\leq n$, and $I_n$ is generated by $\b …
Matthew Pressland's user avatar
2 votes
Accepted

Calabi-Yau algebra for finite dimensional algebras

It is not particularly productive to think about finite-dimensional Calabi–Yau algebras, at least if you are grading everything in degree $0$ (and possibly even if you have a more interesting grading— …
Matthew Pressland's user avatar
3 votes
Accepted

How to get that $\Omega^2_{\Lambda}(N) \cong \textrm{Hom}_A(M,Y)$?

This is an application of the Yoneda lemma. There is an exact sequence $$0\to\Omega^2_\Lambda(N)\to P_1\to P_0\to N\to0$$ with $P_i$ projective. By definition of $\Lambda$, it follows that $P_i=\ope …
Matthew Pressland's user avatar
5 votes

Quiver representations of type $D_n$ mutation class

Up to possibly learning some new technology, you can get a good answer to this question using the cluster category of type $D_n$ (or indeed of any Dynkin type). Given a Dynkin quiver $Q$, its associat …
Matthew Pressland's user avatar
8 votes
0 answers
367 views

When is a $2$-Calabi–Yau triangulated category the cluster category of a QP?

Keller–Reiten's main theorem in Acyclic Calabi–Yau categories implies that if $\mathcal{C}$ is a $2$-Calabi–Yau (algebraic) triangulated category admitting a cluster-tilting object $T$ such that the q …
Matthew Pressland's user avatar
5 votes
1 answer
569 views

When is the category of Gorenstein projective $R$-modules Frobenius?

Let $R$ be a ring (associative with unit, but not necessarily commutative, and definitely not necessarily Noetherian.) Then the category $\operatorname{GP}(R)$ consists of those $R$-modules having a c …
Matthew Pressland's user avatar
3 votes

(Non-)formality for ADE preprojective algebras

This is a case in which various heuristics about the 'niceness' of ADE quivers can interfere with each other. One result in this area that might conform to your expectations is that the algebra $\math …
Matthew Pressland's user avatar
7 votes

A question about the quivers with potentials

It seems an answer to your question may be given by the theory of species with potential; a species is a kind of generalisation of the path algebra of a quiver, designed so that the representation-fin …
Matthew Pressland's user avatar
7 votes
Accepted

What is the status of a problem about cluster categories?

For $H$ the path algebra of a 'star-shaped' quiver having three legs with lengths $r$, $s$, $t$, an answer seems to be implicit in Lamberti's combinatorial model for the cluster category: https://arx …
Matthew Pressland's user avatar
1 vote
Accepted

Auslander-Reiten theory for Gorenstein algebras

This is only a partial answer: For Q1, you might be interested in the examples in the papers arXiv:math/0609138 and arXiv:1309.7301, which both give several examples of AR quivers of categories of Go …
Matthew Pressland's user avatar

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