Determine whether 11 colors suffice for all biplanar graphs

Determine whether every biplanar graph is 11-colorable, resolving the explicitly stated uncertainty about whether 11 colors suffice.

Background

The paper states that the largest chromatic number of a biplanar graph is known to lie between 9 and 12. Although the paper proves that biplanar graphs with independence number at most 2 are 9-colorable, it does not determine the general maximum chromatic number. The cited conjecture that the answer is 11 and the unresolved status of 11-colorability remain outside the paper’s results.