Six-column recursive-line values beyond sixteen rows

Determine z_{RL}(m,6) for every integer m\ge17, and establish whether z_{RL}(m,6)=\left\lfloor(7m+15)/2\right\rfloor for every m\ge15.

Background

Exact values are obtained in the paper only for six-column instances with 6\le m\le16. For m\ge15, the universal cell bound becomes \left\lfloor(7m+15)/2\right\rfloor, and the constructions for m=15 and m=16 attain it.

The finite computations presented do not establish that this upper bound remains attainable for all larger numbers of rows, leaving the general six-column sequence unresolved.

References

Determine $z_{RL}(m,6)$ for $m\ge17$. In particular, is

z_{RL}(m,6)=\left\lfloor\frac{7m+15}{2}\right\rfloor

for every $m\ge15$?

— Is the Signed Zarankiewicz Number the Same as the Recursive-line Zarankiewicz Number?  (2609.20071 - Chen et al., 17 Sep 2026) in Section 5, item 4, “Open Problems”