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Hauptverfasser: Pąk, Karol, Kaliszyk, Cezary
Format: Preprint
Veröffentlicht: 2024
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Online-Zugang:https://arxiv.org/abs/2410.00065
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author Pąk, Karol
Kaliszyk, Cezary
author_facet Pąk, Karol
Kaliszyk, Cezary
contents The proper class of Conway's surreal numbers forms a rich totally ordered algebraically closed field with many arithmetic and algebraic properties close to those of real numbers, the ordinals, and infinitesimal numbers. In this paper, we formalize the construction of Conway's numbers in Mizar using two approaches and propose a bridge between them, aiming to combine their advantages for efficient formalization. By replacing transfinite induction-recursion with transfinite induction, we streamline their construction. Additionally, we introduce a method to merge proofs from both approaches using global choice, facilitating formal proof. We demonstrate that surreal numbers form a field, including the square root, and that they encompass subsets such as reals, ordinals, and powers of $ω$. We combined Conway's work with Ehrlich's generalization to formally prove Conway's Normal Form, paving the way for many formal developments in surreal number theory.
format Preprint
id arxiv_https___arxiv_org_abs_2410_00065
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Conway Normal Form: Bridging Approaches for Comprehensive Formalization of Surreal Numbers
Pąk, Karol
Kaliszyk, Cezary
Logic in Computer Science
The proper class of Conway's surreal numbers forms a rich totally ordered algebraically closed field with many arithmetic and algebraic properties close to those of real numbers, the ordinals, and infinitesimal numbers. In this paper, we formalize the construction of Conway's numbers in Mizar using two approaches and propose a bridge between them, aiming to combine their advantages for efficient formalization. By replacing transfinite induction-recursion with transfinite induction, we streamline their construction. Additionally, we introduce a method to merge proofs from both approaches using global choice, facilitating formal proof. We demonstrate that surreal numbers form a field, including the square root, and that they encompass subsets such as reals, ordinals, and powers of $ω$. We combined Conway's work with Ehrlich's generalization to formally prove Conway's Normal Form, paving the way for many formal developments in surreal number theory.
title Conway Normal Form: Bridging Approaches for Comprehensive Formalization of Surreal Numbers
topic Logic in Computer Science
url https://arxiv.org/abs/2410.00065