Representation embeddings and the third Brauer–Thrall conjecture
We prove that every representation-infinite finite-dimensional algebra over an algebraically closed field has an indecomposable module of each infinite dimension.
Papers
You can also find my papers (preprints) on my arXiv page.
Domestic conferences and technical reports (speech synthesis)
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齋藤佑樹, Wen-Chin Huang, 榎本悠久, 今井柊平, Human Fooling Rateテストに基づく最先端の日本語テキスト音声合成モデルの評価および分析, 情報処理学会研究報告, 2026-SLP-160, 5 pages, June 2026. Links: paper, program.
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今井柊平, 榎本悠久, 金子剛士, 中村泰貴, 系列整合性評価に特化した高難度日本語テキスト音声合成コーパスの検討, 日本音響学会2025年秋季研究発表会, 1-Q-48, September 10, 2025. Links: paper, dataset, GitHub.
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榎本悠久, 今井柊平, 金子剛士, 中村泰貴, 追加学習不要な TTS モデル操作に向けたモデルマージとタスク算術の検討, 日本音響学会2025年秋季研究発表会, 1-Q-47, September 10, 2025. Link: program.
Preprints
Reflexive equivalence and reflexive-minimal algebras
We classify reflexive equivalence classes of finite-dimensional algebras using a unique basic reflexive-minimal algebra.
Magnitude of module categories and special biserial algebras
We prove the magnitude conjecture for representation-finite algebras over an algebraically closed field, with equality precisely for special biserial algebras.
On the homological conjectures for Artin algebras
We prove global equivalences among homological conjectures for Artin algebras and answer a question of Chen and Xi on derived invariance.
A counterexample to the periodicity conjecture for finite-dimensional algebras
We construct a non-periodic algebra all of whose simple modules are periodic.
Finiteness and growth of brick chain filtrations
We prove finiteness of Ringel’s brick chain filtrations and show that their number can grow exponentially in the square of composition length.
The Cartan determinant conjecture for representation-finite algebras
We prove the Cartan determinant conjecture for representation-finite algebras over an algebraically closed field.
An equidistribution conjecture for quotient-closed and submodule-closed subcategories
We propose the quotient–submodule equidistribution conjecture and prove it for several classes of representation-finite algebras.
IE-closed subcategories of commutative rings are torsion-free classes
I proved the title
Maximal self-orthogonal modules and a new generalization of tilting modules
Study maximal self-orthogonal modules, a new generalization of tilting modules = projectively Wakamatsu tilting modules, and Wakamatsu tilting modules
Grothendieck monoids of extriangulated categories
Study the Grothendieck monoid of an extriangulated category.
Publications
Image-extension-closed subcategories of module categories of hereditary algebras
Study subcategories of a module category closed under images and extensions.
From the lattice of torsion classes to the posets of wide subcategories and ICE-closed subcategories
Compute the posets of wide subcats and ICE-closed subcats from the lattice of torsion classes
Intervals of s-torsion pairs in extriangulated categories with negative first extensions
Unify bijections of the form “Interval poset of torsion pairs is isomorphic to the poset of torsion pairs in another subcategory” in the framework of extriangulated categories.
Rigid modules and ICE-closed subcategories in quiver representations
Established a bijection between Image-Cokernel-Extension-closed (ICE-closed) subcats in mod kQ and rigid kQ-modules
The Jordan-Hölder property and Grothendieck monoids of exact categories
I consider when an exact category satisfies the Jordan-Hölder property, (JHP).
Monobrick, a uniform approach to torsion-free classes and wide subcategories
Motivated by the study of simple objects of exact categories, I proposed the notion of monobricks, which enables us to study wide subcategories and torsion-free classes simultaneously.
Schur’s lemma for exact categories implies abelian
I proved the title.
ICE-closed subcategories and wide τ-tilting modules
Study Image-Cokernel-Extension closed subcategories of module categories using the poset of torsion classes and τ-tilting theory.
Classifying substructures of extriangulated categories via Serre subcategories
Classified a possible extriangulated substructures on a given extriangulated category using functor category
Bruhat inversions in Weyl groups and torsion-free classes over preprojective algebras
For torsion-free classes over preprojective algebras and path algebras of Dynkin type, I classify simple objects using the root system.
Relations for Grothendieck groups and representation-finiteness
Rep-fin v.s. “AR seq generate relations for K_0” in exact categories.
Classifications of exact structures and Cohen-Macaulay-finite algebras
I classify possible exact structures on a given additive category by using functor category, and give applications to CM-finite Iwanaga-Gorenstein algebras.
Classifying exact categories via Wakamatsu tilting
Study the Morita type theorem for exact categories. The Ext-perpendicular category of cotilting modules are precisely exact category with progen & inj cogen & higher kernels.
Published proceedings
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H. Enomoto, The Jordan-Hölder property, Grothendieck monoids and Bruhat inversions, Ring Theory 2019, Proceedings of the Eighth China–Japan–Korea International Symposium on Ring Theory (2021), 103–-112.
This is a survey article of this JHP paper. Link: journal