Simutaneously vanishing higher derived limits without large cardinals

Abstract

A question dating to Sibe Mardešić and Andrei Prasolov's 1988 work Strong homology is not additive, and motivating a considerable amount of set theoretic work in the ensuing years, is that of whether it is consistent with the ZFC axioms for the higher derived limits ${\lim }^n$ $(n>0)$ of a certain inverse system $\mathbf{A}$ indexed by ${}^{\omega }\omega$ to simultaneously vanish. An equivalent formulation of this question is that of whether it is consistent for all $n$-coherent families of functions indexed by ${}^{\omega }\omega$ to be trivial. In this paper, we prove that, in any forcing extension given by adjoining ${\beth }_{\omega }$-many Cohen reals, ${\lim }^n\mathbf{A}$ vanishes for all $n>0$. Our proof involves a detailed combinatorial analysis of the forcing extension and repeated applications of higher dimensional $\Delta$-system lemmas. This work removes all large cardinal hypotheses from the main result of arXiv:1907.11744 and substantially reduces the least value of the continuum known to be compatible with the simultaneous vanishing of ${\lim }^n\mathbf{A}$ for all $n>0$.

30 pages, 1 figure

References in corpus (1)

• The Cohomology of the Ordinals I: Basic Theory and Consistency Results