# Siran, Jozef

## Crossing sequences ★★

Author(s): Archdeacon; Bonnington; Siran

**Conjecture**Let be a sequence of nonnegative integers which strictly decreases until .

Then there exists a graph that be drawn on a surface with orientable (nonorientable, resp.) genus with crossings, but not with less crossings.

Keywords: crossing number; crossing sequence