Search arXiv⌕ Search

arXiv · 2610.22002

Indiscernible Extraction in Theories with Bounded $k$-splitting

Abstract

Hanson introduced the class of theories with bounded $k$-splitting, a higher-arity notion of stability, and proved an indiscernible extraction result for those theories assuming the existence of a $k$-ineffable cardinal. In this article, we show that the conclusion of Hanson's theorem is equivalent to the weaker assertion that there exists a weakly compact cardinal, as well as prove additional indiscernible extraction results for these theories in ZFC. Finally, we show that Hanson's construction of total bounded ultraimaginary Morley sequences in theories with bounded $k$-splitting follows from ZFC.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Connor Watson. 2026-10-15. Indiscernible Extraction in Theories with Bounded $k$-splitting. https://arxiv.org/abs/2610.22002

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

Extended Frege proofs, circuits and rewriting

Inspired by a statement about Extended Frege proof systems by Jain and Jin (FOCS 2022) we prove that: - there is a p-time binary relation $\approx$ between circuits that implies their logical equivalence, - if the equivalence $C \equiv D$ has an Extended Frege or a Circuit Frege proof with $k$ steps then there is a chain of circuits $E_i$ $$ C = E_0 \approx \dots \approx E_t = D $$ with $t \le O(k \log k)$, and the total size of the chain is bounded above by $(k+|C|+|D|)^{O(1)}$.

math.LO↗

Canonical expansions of $\mathbb R_{\mathcal Q}$-germs

Let $\mathcal{H}_{\mathcal{Q}}$ be the field of unary germs at $0^+$ definable in the quasianalytic o-minimal structure $\mathbb{R}_{\mathcal{Q}}$ of Kaiser-Rolin-Speissegger. We construct a canonical ordered differential-field embedding of $\mathcal{H}_{\mathcal{Q}}$ into the field of natural-support generalized Laurent series. Every unary germ has a unique such asymptotic expansion, and bounded germs have expansions with only nonnegative exponents. A germ admits a convergent generalized Laurent-series representation exactly when its canonical expansion converges; in that case, every convergent representation with well-ordered support is canonical. We also prove that $\mathbb{R}_{\mathcal{Q}}$ is branching in the sense of Dembner [1]. A nonresonant hyperbolic saddle with divergent Dulac series yields a bounded positive real-analytic $\mathbb{R}_{\mathcal{Q}}$-definable germ whose canonical generalized power series diverges. This gives a negative answer to a question of Dembner asking whether every unary germ definable in a branching structure admits a convergent generalized power-series representation. Nevertheless, every bounded unary $\mathbb{R}_{\mathcal{Q}}$-germ has a canonical formal generalized power-series expansion. Consequently, the convergent germs form a proper ordered differential subfield of $\mathcal{H}_{\mathcal{Q}}$.

math.LO↗