Answers are grounded in this paper and cite their sources.
Article On a family of two-level preconditionings of the incomplete block factorization type was published on January 1, 1986 in the journal Russian Journal of Numerical Analysis and Mathematical Modelling (volume 1, issue 4).
No takes yet. Share an insight, caveat, or question.
Kolotilina et al. (1986) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: