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Equivalence between k-compact generation of stable oo-categories and k-well generation of their homotopy categories

Establish that a stable presentable oo-category E is k-compactly generated if and only if its homotopy category Ho(E) is k-well generated for the same regular cardinal k; specifically, prove the converse implication that Ho(E) being k-well generated implies that E is k-compactly generated (and, more generally, that Lemma A.8(b) holds for any presentable E).

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Background

The authors prove one direction (Proposition A.10): if E is k-compactly generated, then Ho(E) is k-well generated. They point out the desirability of a full equivalence for the same k but could only establish one implication.

Such an equivalence would align cardinal-relative generation notions between stable oo-categories and their triangulated homotopy categories, streamlining the transfer of structural results across settings.

References

By definition though, 'presentable' means k-compactly generated for some regular k; so it would be nice to show that & is k-compactly generated iff Ho(E) is k-well generated (for the same k!). This boils down to showing that part (b) of the lemma holds in a general presentable &. Unfortunately, we can only prove one implication.

Stratification in equivariant Kasparov theory (2412.21109 - Dell'Ambrogio et al., 30 Dec 2024) in Remark A.9, Appendix A