# The shear construction

## TL;DR

This paper introduces a higher rank shear construction method for building solvable Lie algebras from Euclidean spaces, enabling the creation of geometric structures like G2 and semi-Kähler on these algebras.

## Contribution

It generalizes the shear construction to higher ranks using vector bundles with flat connections, allowing systematic construction of all solvable Lie algebras from bf6n spaces.

## Key findings

- Constructed solvable Lie algebras via successive shears.
- Obtained geometric structures such as calibrated G2 and semi-Kähler on these algebras.
- Classified G2-structures on specific Lie algebra forms.

## Abstract

The twist construction is a method to build new interesting examples of geometric structures with torus symmetry from well-known ones. In fact it can be used to construct arbitrary nilmanifolds from tori. In our previous paper, we presented a generalization of the twist, a shear construction of rank one, which allowed us to build certain solvable Lie algebras from $\mathbb{R}^n$ via several shears. Here, we define the higher rank version of this shear construction using vector bundles with flat connections instead of group actions. We show that this produces any solvable Lie algebra from $\mathbb{R}^n$ by a succession of shears. We give examples of the shear and discuss in detail how one can obtain certain geometric structures (calibrated $\mathrm{G}_2$, co-calibrated $\mathrm{G}_2$ and almost semi-K\"ahler) on two-step solvable Lie algebras by shearing almost Abelian Lie algebras. This discussion yields a classification of calibrated $\mathrm{G}_2$-structures on Lie algebras of the form $(\mathfrak{h}_3\oplus \mathbb{R}^3)\rtimes \mathbb{R}$.