Deterministic forgetting planar automata are more powerful than non-deterministic finite-state planar automata.

Petr Jiricka Jaroslav Král Deterministic forgetting planar automata are more powerful than non-deterministic finite-state planar automata. 71-80 1999 conf/dlt/1999 Developments in Language Theory db/conf/dlt/dlt1999.html#JirickaK99