  A pushdown vector addition system with states (PVASS) extends the model of
vector addition systems with a pushdown stack. The algorithmic analysis of
PVASS has applications such as static analysis of recursive programs
manipulating integer variables. Unfortunately, reachability analysis, even for
one-dimensional PVASS is not known to be decidable. We relax the model of
one-dimensional PVASS to make the counter updates continuous and show that in
this case reachability, coverability, and boundedness are decidable in
polynomial time. In addition, for the extension of the model with lower-bound
guards on the states, we show that coverability and reachability are in NP, and
boundedness is in coNP.
