On the Length of Strongly Monotone Descending Chains over $\mathbb{N}^d$

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Hauptverfasser: Schmitz, Sylvain, Schütze, Lia
Format: Preprint
Veröffentlicht: 2023
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author Schmitz, Sylvain
Schütze, Lia
author_facet Schmitz, Sylvain
Schütze, Lia
contents A recent breakthrough by Künnemann, Mazowiecki, Schütze, Sinclair-Banks, and Wegrzycki (ICALP, 2023) bounds the running time for the coverability problem in $d$-dimensional vector addition systems under unary encoding to $n^{2^{O(d)}}$, improving on Rackoff's $n^{2^{O(d\lg d)}}$ upper bound (Theor. Comput. Sci., 1978), and provides conditional matching lower bounds. In this paper, we revisit Lazić and Schmitz' "ideal view" of the backward coverability algorithm (Inform. Comput., 2021) in the light of this breakthrough. We show that the controlled strongly monotone descending chains of downwards-closed sets over $\mathbb{N}^d$ that arise from the dual backward coverability algorithm of Lazić and Schmitz on $d$-dimensional unary vector addition systems also enjoy this tight $n^{2^{O(d)}}$ upper bound on their length, and that this also translates into the same bound on the running time of the backward coverability algorithm. Furthermore, our analysis takes place in a more general setting than that of Lazić and Schmitz, which allows to show the same results and improve on the 2EXPSPACE upper bound derived by Benedikt, Duff, Sharad, and Worrell (LICS, 2017) for the coverability problem in invertible affine nets.
format Preprint
id arxiv_https___arxiv_org_abs_2310_02847
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle On the Length of Strongly Monotone Descending Chains over $\mathbb{N}^d$
Schmitz, Sylvain
Schütze, Lia
Data Structures and Algorithms
Computational Complexity
Logic in Computer Science
F.3.1; F.2
A recent breakthrough by Künnemann, Mazowiecki, Schütze, Sinclair-Banks, and Wegrzycki (ICALP, 2023) bounds the running time for the coverability problem in $d$-dimensional vector addition systems under unary encoding to $n^{2^{O(d)}}$, improving on Rackoff's $n^{2^{O(d\lg d)}}$ upper bound (Theor. Comput. Sci., 1978), and provides conditional matching lower bounds. In this paper, we revisit Lazić and Schmitz' "ideal view" of the backward coverability algorithm (Inform. Comput., 2021) in the light of this breakthrough. We show that the controlled strongly monotone descending chains of downwards-closed sets over $\mathbb{N}^d$ that arise from the dual backward coverability algorithm of Lazić and Schmitz on $d$-dimensional unary vector addition systems also enjoy this tight $n^{2^{O(d)}}$ upper bound on their length, and that this also translates into the same bound on the running time of the backward coverability algorithm. Furthermore, our analysis takes place in a more general setting than that of Lazić and Schmitz, which allows to show the same results and improve on the 2EXPSPACE upper bound derived by Benedikt, Duff, Sharad, and Worrell (LICS, 2017) for the coverability problem in invertible affine nets.
title On the Length of Strongly Monotone Descending Chains over $\mathbb{N}^d$
topic Data Structures and Algorithms
Computational Complexity
Logic in Computer Science
F.3.1; F.2
url https://arxiv.org/abs/2310.02847