Search arXivSearch

arXiv · 2206.11099

Spectral subspaces of spectra of Abelian lattice-ordered groups in size aleph one

Abstract

It is well known that the lattice Idc G of all principal {\ell}-ideals of any Abelian {\ell}-group G is a completely normal distributive 0-lattice, and that not every completely normal distributive 0-lattice is a homomorphic image of some Idc G, via a counterexample of cardinality $\aleph 2. We prove that every completely normal distributive 0-lattice with at most $\aleph 1 elements is a homomorphic image of some Idc G. By Stone duality, this means that every completely normal generalized spectral space, with at most $\aleph 1 compact open sets, is homeomorphic to a spectral subspace of the {\ell}-spectrum of some Abelian {\ell}-group.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Miroslav Ploscica, Friedrich Wehrung. 2022-06-20. Spectral subspaces of spectra of Abelian lattice-ordered groups in size aleph one. https://arxiv.org/abs/2206.11099

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

On Borel sets in ideal topologies

We study the Borel and analytic subsets of the spaces ${}^κκ$ and ${}^κ2$ endowed with ideal topologies, where $κ$ is a regular uncountable cardinal, thereby addressing some open problems of the literature. We provide a systematic analysis of the Borel hierarchy for an arbitrary ideal topology. In particular, we formulate a sufficient condition ensuring that the hierarchy does not collapse, demonstrate that every Borel set in such a topology is analytic, and establish the existence of a set that is not Borel. Our main result shows that, when the underlying ideal contains an unbounded subset, the collection of analytic sets coincides with the full power set of the ambient space. Finally, we prove that the Approximation Lemma holds in the setting of ideal topologies.

math.LO

Inquisitive first-order logic is neither compact nor recursively axiomatizable

Inquisitive first-order logic is an extension of classical first-order logic with formulas regimenting first-order questions, such as "whether all objects are P", "which objects are P", and "what is one object that is P". Since it was first developed in 2009, two major meta-theoretical questions about this logic have remained open, in spite of significant efforts. The first concerns compactness: if a conclusion follows from a set of premises, does it always follow from some finite subset? The second concerns the computational status of validity: is the set of validities recursively enumerable, or equivalently, does the logic admit a recursive axiomatization? We settle both questions in the negative, showing that inquisitive first-order logic is neither compact nor recursively axiomatizable. Furthermore, we prove that it violates another signature property of first-order logic, namely, Craig interpolation. We discuss the significance of our results, and show how to extend them to a closely related logic, viz., inquisitive team logic.

math.LO

The Borel Distinguishing Number of Schreier Graphs

The Borel distinguishing number $D_B(\mathcal{G})$ of a Borel graph $\mathcal{G}$, recently introduced by Bilge and Kaya, is the minimum number of colors required to break the symmetry of $\mathcal{G}$ in a Borel way. In this paper, we investigate the Borel distinguishing number of Schreier graphs induced by the free part of the shift action $Γ\curvearrowright n^Γ$. We prove that $D_B(\mathcal{G})\le n+1$ for $Γ=\mathbb{Z}^d$ equipped with the standard generators. Moreover, we show that $D_B(\mathcal{G})\ge n+1$ if $ Γ$ is amenable and $ \{γ\in \mathrm{Aut}(\mathrm{Cay}(Γ,S)) \mid γ(e) = e \}$ is non-trivial. We also show that $D_B(\mathcal{G})$ is finite if $Γ$ is finitely generated, and give some applications of our results. These results answer some questions raised by Bilge and Kaya.

math.LO