Infinite lexicographic products of positional objectives

Fuente: arXiv
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Auteurs principaux: Casares, Antonio, Ohlmann, Pierre, Skrzypczak, Michał, Walukiewicz, Igor
Format: Preprint
Publié: 2025
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author Casares, Antonio
Ohlmann, Pierre
Skrzypczak, Michał
Walukiewicz, Igor
author_facet Casares, Antonio
Ohlmann, Pierre
Skrzypczak, Michał
Walukiewicz, Igor
contents This paper contributes to the study of positional determinacy of infinite duration games played on potentially infinite graphs with neutral transitions. Recently, [Ohlmann, TheoretiCS 2023] established that positionality of prefix-independent objectives is preserved by finite lexicographic products. We propose two different notions of infinite lexicographic products indexed by arbitrary ordinals, and extend Ohlmann's result by proving that they also preserve positionality. In the context of one-player positionality, this extends positional determinacy results of [Grädel and Walukiewicz, Logical Methods in Computer Science 2006] to edge-labelled games and arbitrarily many priorities for both Max-Parity and Min-Parity. Moreover, we show that the Max-Parity objectives over countable ordinals are complete for the infinite levels of the difference hierarchy over $Σ^0_2$ and that Min-Parity is complete for the class $Σ^0_3$. We obtain therefore positional languages that are complete for all those levels, as well as new insights about closure under unions and neutral letters.
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id arxiv_https___arxiv_org_abs_2506_14544
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Infinite lexicographic products of positional objectives
Casares, Antonio
Ohlmann, Pierre
Skrzypczak, Michał
Walukiewicz, Igor
Computer Science and Game Theory
This paper contributes to the study of positional determinacy of infinite duration games played on potentially infinite graphs with neutral transitions. Recently, [Ohlmann, TheoretiCS 2023] established that positionality of prefix-independent objectives is preserved by finite lexicographic products. We propose two different notions of infinite lexicographic products indexed by arbitrary ordinals, and extend Ohlmann's result by proving that they also preserve positionality. In the context of one-player positionality, this extends positional determinacy results of [Grädel and Walukiewicz, Logical Methods in Computer Science 2006] to edge-labelled games and arbitrarily many priorities for both Max-Parity and Min-Parity. Moreover, we show that the Max-Parity objectives over countable ordinals are complete for the infinite levels of the difference hierarchy over $Σ^0_2$ and that Min-Parity is complete for the class $Σ^0_3$. We obtain therefore positional languages that are complete for all those levels, as well as new insights about closure under unions and neutral letters.
title Infinite lexicographic products of positional objectives
topic Computer Science and Game Theory
url https://arxiv.org/abs/2506.14544