Slightly Non-Linear Higher-Order Tree Transducers

Fuente: arXiv
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Main Authors: Nguyên, Lê Thành Dũng, Vanoni, Gabriele
Format: Preprint
Published: 2024
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author Nguyên, Lê Thành Dũng
Vanoni, Gabriele
author_facet Nguyên, Lê Thành Dũng
Vanoni, Gabriele
contents We investigate the tree-to-tree functions computed by "affine $λ$-transducers": tree automata whose memory consists of an affine $λ$-term instead of a finite state. They can be seen as variations on Gallot, Lemay and Salvati's Linear High-Order Deterministic Tree Transducers. When the memory is almost purely affine ($\textit{à la}$ Kanazawa), we show that these machines can be translated to tree-walking transducers (and with a purely affine memory, we get a reversible tree-walking transducer). This leads to a proof of an inexpressivity conjecture of Nguyên and Pradic on "implicit automata" in an affine $λ$-calculus. We also prove that a more powerful variant, extended with preprocessing by an MSO relabeling and allowing a limited amount of non-linearity, is equivalent in expressive power to Engelfriet, Hoogeboom and Samwel's invisible pebble tree transducers. The key technical tool in our proofs is the Interaction Abstract Machine (IAM), an operational avatar of Girard's geometry of interaction, a semantics of linear logic. We work with ad-hoc specializations to $λ$-terms of low exponential depth of a tree-generating version of the IAM.
format Preprint
id arxiv_https___arxiv_org_abs_2402_05854
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Slightly Non-Linear Higher-Order Tree Transducers
Nguyên, Lê Thành Dũng
Vanoni, Gabriele
Formal Languages and Automata Theory
Logic in Computer Science
We investigate the tree-to-tree functions computed by "affine $λ$-transducers": tree automata whose memory consists of an affine $λ$-term instead of a finite state. They can be seen as variations on Gallot, Lemay and Salvati's Linear High-Order Deterministic Tree Transducers. When the memory is almost purely affine ($\textit{à la}$ Kanazawa), we show that these machines can be translated to tree-walking transducers (and with a purely affine memory, we get a reversible tree-walking transducer). This leads to a proof of an inexpressivity conjecture of Nguyên and Pradic on "implicit automata" in an affine $λ$-calculus. We also prove that a more powerful variant, extended with preprocessing by an MSO relabeling and allowing a limited amount of non-linearity, is equivalent in expressive power to Engelfriet, Hoogeboom and Samwel's invisible pebble tree transducers. The key technical tool in our proofs is the Interaction Abstract Machine (IAM), an operational avatar of Girard's geometry of interaction, a semantics of linear logic. We work with ad-hoc specializations to $λ$-terms of low exponential depth of a tree-generating version of the IAM.
title Slightly Non-Linear Higher-Order Tree Transducers
topic Formal Languages and Automata Theory
Logic in Computer Science
url https://arxiv.org/abs/2402.05854