The uniform dimension of a monoid with applications to graph algebras

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Bibliographic Details
Title: The uniform dimension of a monoid with applications to graph algebras
Authors: Luiz Gustavo Cordeiro, Daniel Gonçalves, Roozbeh Hazrat
Source: Journal of Algebra. 682:31-59
Publication Status: Preprint
Publisher Information: Elsevier BV, 2025.
Publication Year: 2025
Subject Terms: Rings and Algebras (math.RA), Mathematics - Operator Algebras, FOS: Mathematics, Mathematics - Rings and Algebras, Operator Algebras (math.OA), 16S88
Description: We adapt Goldie's concept of uniform dimensions from module theory over rings to $Γ$-monoids. A $Γ$-monoid $M$ is said to have uniform dimension $n$ if $n$ is the largest number of pairwise incomparable nonzero $Γ$-order ideals contained in $M$. Specializing to the talented monoid of a graph, we show that the uniform dimension provides a rough measure of how the graph branches out. Since for any order ideal $I$, its orthogonal ideal $I^\perp$ is the largest ideal incomparable to $I$, we study the notions of orthogonality and regularity, particularly when $I^{\perp\perp}=I$. We show that the freeness of the action of $\mathbb Z$ on the talented monoid of a graph is preserved under quotienting by a regular ideal. Furthermore, we determine the underlying hereditary and saturated sets that generate these ideals. These results unify recent studies on regular ideals of the corresponding Leavitt path algebras and graph $C^*$-algebras. We conclude that for graphs $E$ and $F$, if there is a $\mathbb Z$-monoid isomorphism $T_E\cong T_F$, then there is a one-to-one correspondence between the regular ideals of the associated Leavitt path algebras $L_K(E)$ and $L_K(F)$ (and similarly, $C^*(E)$ and $C^*(F)$). Since the talented monoid $T_E$ is the positive cone of the graded Grothendieck group $K_0^{gr}(L_K(E))$, this provides further evidence supporting the Graded Classification Conjecture.
Document Type: Article
Language: English
ISSN: 0021-8693
DOI: 10.1016/j.jalgebra.2025.05.042
DOI: 10.48550/arxiv.2502.11226
Access URL: http://arxiv.org/abs/2502.11226
Rights: Elsevier TDM
arXiv Non-Exclusive Distribution
Accession Number: edsair.doi.dedup.....74b070454e49ff2f1812e355fff1fea7
Database: OpenAIRE
Description
Abstract:We adapt Goldie's concept of uniform dimensions from module theory over rings to $Γ$-monoids. A $Γ$-monoid $M$ is said to have uniform dimension $n$ if $n$ is the largest number of pairwise incomparable nonzero $Γ$-order ideals contained in $M$. Specializing to the talented monoid of a graph, we show that the uniform dimension provides a rough measure of how the graph branches out. Since for any order ideal $I$, its orthogonal ideal $I^\perp$ is the largest ideal incomparable to $I$, we study the notions of orthogonality and regularity, particularly when $I^{\perp\perp}=I$. We show that the freeness of the action of $\mathbb Z$ on the talented monoid of a graph is preserved under quotienting by a regular ideal. Furthermore, we determine the underlying hereditary and saturated sets that generate these ideals. These results unify recent studies on regular ideals of the corresponding Leavitt path algebras and graph $C^*$-algebras. We conclude that for graphs $E$ and $F$, if there is a $\mathbb Z$-monoid isomorphism $T_E\cong T_F$, then there is a one-to-one correspondence between the regular ideals of the associated Leavitt path algebras $L_K(E)$ and $L_K(F)$ (and similarly, $C^*(E)$ and $C^*(F)$). Since the talented monoid $T_E$ is the positive cone of the graded Grothendieck group $K_0^{gr}(L_K(E))$, this provides further evidence supporting the Graded Classification Conjecture.
ISSN:00218693
DOI:10.1016/j.jalgebra.2025.05.042