Equivalence of pure infiniteness properties for separable nuclear C*-algebras

Determine whether weak pure infiniteness, pure infiniteness, and strong pure infiniteness are equivalent for every separable nuclear C*-algebra.

Background

The paper introduces two notions for essential extensions into corona algebras: pure infiniteness, defined through Cuntz subequivalence of two copies of each nonzero positive image, and strong O∞O_{\infty}-stability, defined through asymptotically central pairs of isometries. The authors explain that these notions correspond roughly to pure infiniteness and O∞O_{\infty}-stability for C*-algebras.

They note that, although the three standard pure infiniteness notions coincide in the simple case, their equivalence for arbitrary separable nuclear C*-algebras is unresolved. This question concerns the relationship among weak pure infiniteness, pure infiniteness, and strong pure infiniteness in the nonsimple setting.

References

As far as we know, for an arbitrary separable nuclear C*-algebra, it is presently still an open problem whether weak pure infiniteness, pure infiniteness and strong pure infiniteness are equivalent properties (see ).

— A note on purely infinite extensions  (2610.12992 - Ng et al., 9 Oct 2026) in Section 1, paragraph following Definition 1 (the paragraph beginning “Definitions \ref{df:PIExt} (1) and (2)”)