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Toshihisa Urahigashi

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#large language models Open access Oct 2026

Evaluation orders on bracketings in the hyperoperation hierarchy

Let Hr be the Goodstein hyperoperation hierarchy, so that H3 is exponentiation and H4 tetration. For r ≥ 3 the operation is not associative, so the value of Hr(a1, …, an) depends on the bracketing, that is on a binary tree with n leaves. Write T ≤ev U when evr(T) ≤ evr(U) for every assignment of leaf values ≥ 2, and le...

Toshihisa Urahigashi · 0 citations
#large language models Open access Oct 2026

A local non-containment in Step (v) of IUT IV, Theorem 1.10

Step (v) of the proof of Theorem 1.10 in Mochizuki's Inter-universal Teichmüller theory IV bounds, for each tuple of places, the log-volume of the corresponding component of the holomorphic hull of the union of possible images of a Θ-pilot object defined in Corollary 3.12 of the third paper. This note gives an explicit...

Toshihisa Urahigashi · 0 citations
#large language models Open access Oct 2026

A local non-containment in Step (v) of IUT IV, Theorem 1.10

Step (v) of the proof of Theorem 1.10 in Mochizuki's Inter-universal Teichmüller theory IV bounds, for each tuple of places, the log-volume of the corresponding component of the holomorphic hull of the union of possible images of a Θ-pilot object defined in Corollary 3.12 of the third paper. This note gives an explicit...

Toshihisa Urahigashi · 0 citations
#large language models Open access Sep 2026

hyper-tamari: the Lean 4 developments accompanying "Evaluation orders on bracketings in the hyperoperation hierarchy"

The Lean 4 developments accompanying the paper Evaluation orders on bracketings in the hyperoperation hierarchy by Toshihisa Urahigashi. Let H_r be the Goodstein hyperoperation hierarchy (H_1 addition, H_2 multiplication, H_3 exponentiation, H_4 tetration). For r ≥ 3 the operation is non-associative, so the value of a...

Toshihisa Urahigashi · 0 citations

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