Pre-Nichols algebras of one-parameter families of finite Gelfand-Kirillov dimension

TL;DR

This paper classifies pre-Nichols algebras of diagonal type with finite Gelfand-Kirillov dimension, showing most are Nichols algebras and identifying key exceptions with explicit constructions.

Contribution

It proves that most pre-Nichols algebras of finite GK dimension are Nichols algebras, and explicitly constructs the few exceptions, advancing classification efforts.

Findings

Most pre-Nichols algebras of finite GK dimension are Nichols algebras.

Identified and constructed explicit pre-Nichols algebras for exceptions.

Completed the classification of eminent pre-Nichols algebras of diagonal type.

Abstract

Between the braided vector spaces of diagonal type there exist some families whose associated Nichols algebras are infinite dimensional but with finite Gelfand-Kirillov dimension, called one-parameter families. We show that every pre-Nichols algebra of finite Gelfand-Kirillov dimension of this kind with connected diagram is necessarily the corresponding Nichols algebra, up to few exceptions. For each one of these exceptions we present a proper pre-Nichols algebra by generators and relations, and prove that it is the corresponding eminent pre-Nichols algebra. This paper essentially ends the determination of the eminent pre-Nichols algebras of diagonal type, the first step towards the classification of pre-Nichols algebras of diagonal type with finite GKdim.