We fill an apparent gap in the literature by giving a short and self-contained proof that the ordinal of the theory RCA0+WO(σ) is σ^ω , for any ordinal σ satisfying ω⋅σ=σ (e.g., ω^ω , ω^ω^ω , ε0 ). Theories of the form RCA0+WO(σ) are of interest in Proof Theory and Reverse Mathematics because of their connections to a number of well-investigated combinatorial principles related to various subsystems of arithmetic.

A note on the ordinal analysis of RCA0 + WO(σ) / Carlucci, Lorenzo; Mainardi, Leonardo; Rathjen, Michael. - 11558:(2019), pp. 144-155. (Intervento presentato al convegno Computability in Europe 2019 tenutosi a Durham; United Kingdom) [10.1007/978-3-030-22996-2_13].

A note on the ordinal analysis of RCA0 + WO(σ)

Carlucci, Lorenzo
;
Mainardi, Leonardo;
2019

Abstract

We fill an apparent gap in the literature by giving a short and self-contained proof that the ordinal of the theory RCA0+WO(σ) is σ^ω , for any ordinal σ satisfying ω⋅σ=σ (e.g., ω^ω , ω^ω^ω , ε0 ). Theories of the form RCA0+WO(σ) are of interest in Proof Theory and Reverse Mathematics because of their connections to a number of well-investigated combinatorial principles related to various subsystems of arithmetic.
2019
Computability in Europe 2019
ordinals; proof theory; well-ordering
04 Pubblicazione in atti di convegno::04b Atto di convegno in volume
A note on the ordinal analysis of RCA0 + WO(σ) / Carlucci, Lorenzo; Mainardi, Leonardo; Rathjen, Michael. - 11558:(2019), pp. 144-155. (Intervento presentato al convegno Computability in Europe 2019 tenutosi a Durham; United Kingdom) [10.1007/978-3-030-22996-2_13].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1351100
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