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Ladders and Squares

Ladders and Squares

来源:Arxiv_logoArxiv
英文摘要

In 1984, Ditor asked two questions: (1) For each $n\in\omega$ and infinite cardinal $\kappa$, is there a join-semilattice of breadth $n+1$ and cardinality $\kappa^{+n}$ whose principal ideals have cardinality $< \kappa$? (2) For each $n \in \omega$, is there a lower-finite lattice of cardinality $\aleph_{n}$ whose elements have at most $n+1$ lower covers? We show that both questions have positive answers under the axiom of constructibility, and hence consistently with $\mathsf{ZFC}$. More specifically, we derive the positive answers from assuming that $\square_\kappa$ holds for enough $\kappa$'s.

Lorenzo Notaro

数学

Lorenzo Notaro.Ladders and Squares[EB/OL].(2025-05-01)[2025-05-25].https://arxiv.org/abs/2505.00414.点此复制

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