A note on dual Dedekind finiteness

Abstract A set $A$ is dually Dedekind finite if every surjection from $A$ onto $A$ is injective; otherwise, $A$ is dually Dedekind infinite. It is proved consistent with $\mathsf{ZF}$ (i.e. the Zermelo–Fraenkel set theory without the axiom of choice) that there exists a family $\langle A_{n}\rangle _{n\in \omega }$ of sets such that, for all $n\in \omega $, $A_{n}^{n}$ is dually Dedekind finite whereas $A_{n}^{n+1}$ is dually Dedekind infinite. This resolves a question that was left open in (Classes of Dedekind finite cardinals. Fund. Math. 1974;84:187–208).

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Publication Details

Journal
Logic Journal of IGPL
Published
2025-08-15
DOI
https://doi.org/10.1093/jigpal/jzaf069
Citations
1
Primary Topic
Advanced Topology and Set Theory
Type
article
Field-Weighted Citation Impact
4.09
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article

A note on dual Dedekind finiteness

Guozhen Shen, Ruihuan Mao
1 citations
Logic Journal of IGPL
Advanced Topology and Set Theory
4.09
article

A note on dual Dedekind finiteness

Guozhen Shen, Ruihuan Mao
article en
1 citations

Abstract

Abstract A set $A$ is dually Dedekind finite if every surjection from $A$ onto $A$ is injective; otherwise, $A$ is dually Dedekind infinite. It is proved consistent with $\mathsf{ZF}$ (i.e. the Zermelo–Fraenkel set theory without the axiom of choice) that there exists a family $\langle A_{n}\rangle _{n\in \omega }$ of sets such that, for all $n\in \omega $, $A_{n}^{n}$ is dually Dedekind finite whereas $A_{n}^{n+1}$ is dually Dedekind infinite. This resolves a question that was left open in (Classes of Dedekind finite cardinals. Fund. Math. 1974;84:187–208).

Logic Journal of IGPLVol. 33(5)
Nankai University (CN), Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) (CN)
Openalex Percentile: Top 6%
Advanced Topology and Set Theory
4.09
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