Peter F. Faul ; Graham Manuell - Machine Space I: Weak exponentials and quantification over compact spaces

lmcs:12327 - Logical Methods in Computer Science, April 7, 2026, Volume 22, Issue 2 - https://doi.org/10.46298/lmcs-22(2:2)2026
Machine Space I: Weak exponentials and quantification over compact spacesArticle

Authors: Peter F. Faul ; Graham Manuell

Topology may be interpreted as the study of verifiability, where opens correspond to semi-decidable properties. In this paper we make a distinction between verifiable properties themselves and processes which carry out the verification procedure. The former are simply opens, while we call the latter \emph{machines}. Given a frame presentation $\mathcal{O} X = \langle G \mid R\rangle$ we construct a space of machines $Σ^{Σ^G}$ whose points are given by formal combinations of basic machines corresponding to generators in $G$. This comes equipped with an `evaluation' map making it a weak exponential with base $Σ$ and exponent $X$. When it exists, the true exponential $Σ^X$ occurs as a retract of machine space. We argue this helps explain why some spaces are exponentiable and others not. We then use machine space to study compactness by giving a purely topological version of Escardó's algorithm for universal quantification over compact spaces in finite time. Finally, we relate our study of machine space to domain theory and domain embeddings.


Volume: Volume 22, Issue 2
Published on: April 7, 2026
Imported on: September 25, 2023
Keywords: General Topology, Logic in Computer Science

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