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Questions tagged [hardy-fields]

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1 answer
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In surreal numbers, do the automorphisms allow us to define $\omega_2=\partial(\omega_1)$?

Consider surreal numbers as an H-field with operation of derivation. In such setting for any surreal number $\alpha$ such that $0<\alpha<e^\omega$, $\partial(\alpha)<\alpha$ and for $\alpha&...
-1 votes
1 answer
272 views

Why is it said that all surreal numbers with birthdate $<\omega_1$ are isomorphic to a Hardy field?

In this answer I have encountered with the following statement: Assuming CH, every maximal Hardy field is isomorphic to $(\bf{No}(\omega_1), \partial_{\omega_1})$, where $\bf{No}(\omega_1)$ is the ...
1 vote
1 answer
205 views

Representing the set of rationals $\mathbb{Q}$ as a germ or surreal number

Let us define natural equivalence between elements of Hardy fields and integrals of Dirac comb-like functions. Let us assume a natural embedding of Hardy field into surreal numbers ($[x]=\omega$). ...
8 votes
2 answers
963 views

In surreal numbers, what exactly is $\omega_1$?

This answer refers to $\omega_1$ in context of surreal numbers, and calls it "first uncountable ordinal". But what exactly does it mean? How can it be represented in the $\{L|R\}$ form? How ...