arXiv subjects

Elvis Torres Pérez

Publications and source records attributed to Elvis Torres Pérez.

8 recordsLinked to original sources

arXiv2026

Remarks on refined scissors congruence group and the third homology of $\mathrm{SL}_2$

This work revisits the key sufficient conditions on a ring $A$ that guarantee the existence of the exact sequence \[ H_3(\mathrm{SM}_2(A), \mathbb{Z})\to H_3(\mathrm{SL}_2(A), \mathbb{Z}) \to \mathcal{RB}(A) \to 0 \] and of the isomorphism \[ H_3(\mathrm{SL}_2(A), \mathrm{SM}_2(A); \mathbb{Z}) \simeq \mathcal{RP}_1(A). \] We show that there are rings which satisfy the relations above but do not satisfy the condition that -1 is an square, for example some rings $\mathbb{Z}[\frac{1}{m}]$ and finite local rings. In addition, we study the special case of non-dyadic local fields with characteristic not 2, obtaining a refined Bloch-Wigner exact sequence when -1 is not an square.

math.KT↗

arXiv2025

The low dimensional homology groups of the elementary group of degree two

In this article we study the first, the second and the third homology groups of the elementary group $\textrm{E}_2(A)$, where $A$ is a commutative ring. In particular, we prove a refined Bloch-Wigner type exact sequence over a semilocal ring (with some mild restriction on its residue fields) such that $-1\in (A^{\times})^2$ or $|A^{\times}/(A^{\times})^2|\leq 4$.

math.KT↗

arXiv2025

The third homology of projective special linear group of degree two

In this paper we investigate the third homology of the projective special linear group ${\rm PSL}_2(A)$. As a result of our investigation we prove a projective refined Bloch-Wigner exact sequence over certain class of rings. The projective Bloch-Wigner exact sequence over an algebraically closed field of characteristic zero is a classical result and has many application in algebra, number theory and geometry.

math.KT↗

arXiv2024

The low dimensional homology of projective linear group of rank two

In this article we study the low dimensional homology of the projective linear group $\textrm{PGL}_2(A)$ over a commutative ring $A$. In particular, we prove a Bloch-Wigner type exact sequence over local domains. As applications we prove that $H_2(\textrm{PGL}_2(A),\mathbb{Z}\left[\frac{1}{2}\right])\simeq K_2(A)\left[\frac{1}{2}\right]$ and $H_3(\textrm{PGL}_2(A),\mathbb{Z}\left[\frac{1}{2}\right])\simeq K_3^{\textrm{ind}}(A)\left[\frac{1}{2}\right]$ provided $|A/\mathcal{m}_A|\neq 2,3,4,8$.

math.KT↗

arXiv2024

The abelianization of the elementary group of rank two

For an arbitrary ring $A$, we study the abelianization of the elementary group $\textrm{E}_2(A)$. In particular, we show that for a commutative ring $A$ there exists an exact sequence \[ K_2(2,A)/C(2,A) \to A/M \to \textrm{E}_2(A)^\textrm{ab} \to 1, \] where $C(2,A)$ is the central subgroup of the Steinberg group $\textrm{St}(2,A)$ generated by the Steinberg symbols and $M$ is the additive subgroup of $A$ generated by $x(a^2-1)$ and $3(b+1)(c+1)$, with $x\in A$, $a,b,c \in A^{\times}$.

math.KT↗

arXiv2024

On the connections between the low dimensional homology groups of $\textrm{SL}_2$ and $\textrm{PSL}_2$

In this article we study the low dimensional homology groups of the special linear group $\textrm{SL}_2(A)$ and the projective special linear group $\textrm{PSL}_2(A)$, $A$ a domain, through the natural surjective map $\textrm{SL}_2(A) \to \textrm{PSL}_2(A)$. In particular, we study the connection of the first, the second and the third homology groups of these groups over euclidean domains $\mathbb{Z}[\frac{1}{m}]$, $m$ a square free integer, and local domains.

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arXiv2024

A Refined scissors congruence group and the third homology of $\textrm{SL}_2$

There is a natural connection between the third homology of $\textrm{SL}_2(A)$ and the refined Bloch group $\mathcal{RB}(A)$ of a commutative ring $A$. In this article we investigate this connection and as the main result we show that if $A$ is a universal $\textrm{GE}_2$-domain such that $-1 \in A^{\times 2}$, then we have the exact sequence $H_3(\textrm{SM}_2(A),\mathbb{Z}) \to H_3(\textrm{SL}_2(A),\mathbb{Z}) \to \mathcal{RB}(A) \to 0$, where $\textrm{SM}_2(A)$ is the group of monomial matrices in $\textrm{SL}_2(A)$. Moreover we show that $\mathcal{RP}_1(A)$, the refined scissors congruence group of $A$, naturally is isomorph with the relative homology group $H_3(\textrm{SL}_2(A), \textrm{SM}_2(A),\mathbb{Z})$.

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arXiv2023

A refined Bloch-Wigner exact sequence in characteristic 2

Let $A$ be a local domain of characteristic $2$ such that its residue field has more than $64$ elements. Then we find an exact relation between the third integral homology of the group $\mathrm{SL}_2(A)$ and Hutchinson's refined Bloch group $\mathcal{RB}(A)$.

math.KT↗