Quasi-hereditary covers of Temperley-Lieb algebras and relative dominant dimension

TL;DR

This paper investigates the structure of quasi-hereditary covers of Temperley-Lieb algebras, establishing new relationships between relative dominant dimensions, and classifies their connections to Ringel duals of q-Schur algebras, including in the integral case.

Contribution

It provides a novel formula relating relative dominant dimensions in quasi-hereditary algebras and classifies the quasi-hereditary covers of Temperley-Lieb algebras via Ringel duals of q-Schur algebras.

Findings

Relative dominant dimension of regular modules is twice that of characteristic tilting modules.

Complete classification of Temperley-Lieb algebras' quasi-hereditary covers via Ringel duals.

Determination of relative dominant dimension of Schur algebras $S(2, d)$ with respect to tensor powers.

Abstract

Many connections and dualities in representation theory can be explained using quasi-hereditary covers in the sense of Rouquier. The concepts of relative dominant and codominant dimension with respect to a module, introduced recently by the first-named author, are important tools to evaluate and classify quasi-hereditary covers. In this paper, we prove that the relative dominant dimension of the regular module of a quasi-hereditary algebra with a simple preserving duality with respect to a summand $Q$ of a characteristic tilting module equals twice the relative dominant dimension of a characteristic tilting module with respect to $Q$. To resolve the Temperley-Lieb algebras of infinite global dimension, we apply this result to the class of Schur algebras $S(2, d)$ and $Q=V^{\otimes d}$ the $d$-tensor power of the 2-dimensional module and we completely determine the relative dominant dimension of the Schur algebra $S(2, d)$ with respect to $V^{\otimes d}$. The $q$-analogues of these results are also obtained. As a byproduct, we obtain a Hemmer-Nakano type result connecting the Ringel duals of $q$-Schur algebras and Temperley-Lieb algebras. From the point of view of Temperley-Lieb algebras, we obtain the first complete classification of their connection to their quasi-hereditary covers formed by Ringel duals of $q$-Schur algebras. These results are compatible with the integral setup, and we use them to deduce that the Ringel dual of a $q$-Schur algebra over the ring of Laurent polynomials over the integers together with some projective module is the best quasi-hereditary cover of the integral Temperley-Lieb algebra.