Determine the active cop number of planar graphs

Determine the exact value of the active cop number for the class of planar graphs in the Fully Active Cops and Robber game, where both the cops and the robber must move to an adjacent vertex on every turn.

Background

The Fully Active Cops and Robber variant requires all players to move each turn. Prior work by Gromovikov et al. introduced this variant and posed the determination of the active cop number for planar graphs as an open question. In this paper, the authors partially address this by proving an upper bound of 4 on the active cop number of planar graphs, leaving the exact value unresolved.