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arXiv · 1603.00129

The homomorphism lattice induced by a finite algebra

Brian A. Davey·Charles T. Gray·Jane G. Pitkethly
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Abstract

Each finite algebra $\mathbf A$ induces a lattice~$\mathbf L_{\mathbf A}$ via the quasi-order~$\to$ on the finite members of the variety generated by~$\mathbf A$, where $\mathbf B \to \mathbf C$ if there exists a homomorphism from $\mathbf B$ to~$\mathbf C$. In this paper, we introduce the question: `Which lattices arise as the homomorphism lattice $\mathbf L_{\mathbf A}$ induced by a finite algebra $\mathbf A$?' Our main result is that each finite distributive lattice arises as~$\mathbf L_{\mathbf Q}$, for some quasi-primal algebra~$\mathbf Q$. We also obtain representations of some other classes of lattices as homomorphism lattices, including all finite partition lattices, all finite subspace lattices and all lattices of the form $\mathbf L\oplus \mathbf 1$, where $\mathbf L$ is an interval in the subgroup lattice of a finite group.

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Brian A. Davey, Charles T. Gray, Jane G. Pitkethly. 2016-03-01. The homomorphism lattice induced by a finite algebra. https://arxiv.org/abs/1603.00129

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