Simulation Problems Over One-Counter Nets
  One-counter nets (OCN) are finite automata equipped with a counter that can store non-negative integer values, and that cannot be tested for zero. Equivalently, these are exactly 1-dimensional vector addition systems with states. We show that both strong and weak simulation preorder on OCN are PSPACE-complete. 
Piotr Hofman (Cachan), Slawomir Lasota (Warsaw), Richard Mayr   (Edinburgh), Patrick Totzke (Warwick)
cs.LO