Existence of quasi t-fine rings outside the fine class

Determine whether there exists a quasi t-fine ring that is not fine.

Background

A quasi t-fine ring is defined as a ring in which every nonzero element is a sum of a torsion unit and a quasinilpotent element; the paper observes that every t-fine ring is quasi t-fine. Example \ref{ex 33}(3) supplies a quasi t-fine ring, but it is also fine, so it does not resolve whether the quasi t-fine class properly extends the fine class.

The authors explicitly state that the existence of a quasi t-fine ring that is not fine is unknown and formulate it as the first alternative in the concluding problem.

References

Obviously, each $t$-fine ring is a quasi $t$-fine ring, but we do not know whether there exists a quasi $t$-fine ring that is not $t$-fine. Thus, we conclude this paper with the following problem, whose answer is currently unknown to us.

Does there exist a quasi $t$-fine ring that is not fine, and, if not, does there exist a generalized quasi $t$-fine ring that is not generalized fine?

Generalized $t$-Fine and Quasi $t$-Fine Rings  (2609.19882 - Bien et al., 17 Sep 2026) in Section 3, final paragraph and the concluding Problem