| 12 | Trivial [R1959] | In fact, every biplanar graph has a vertex of degree at most 11. |tracked since 2026-07-24 — no movement seen yet
Lower bound, last-listed row
| 9 | Sulanke [G1980] | Constructed as the join of a 6-vertex complete graph and a 5-vertex cycle graph. |tracked since 2026-07-24 — no movement seen yet
Cite this rowBounds Ledger — Maximum Chromatic Number of Biplanar Graphs (27b)
upper bound: 12 (tracked since 2026-07-24 — no movement seen yet)
lower bound: 9 (tracked since 2026-07-24 — no movement seen yet)
Mirrored from teorth/optimizationproblems@2c1968c. These are the last-listed rows of that constant's bounds table — a listing position, not a statement that this bound is the strongest or most recent. A snapshot at that sha, not a live read.
https://u00dxk2.github.io/bounds-ledger/c/27b.html