  The Canadian traveler problem (CTP) is the problem of traversing a given
graph, where some of the edges may be blocked - a state which is revealed only
upon reaching an incident vertex. Originally stated by Papadimitriou and
Yannakakis (1991), the adversarial version of CTP was shown to be
PSPACE-complete, with the stochastic version shown to be #P-hard. We show that
stochastic CTP is also PSPACE-complete: initially proving PSPACE-hardness for
the dependent version of stochastic CTP,and proceeding with gadgets that allow
us to extend the proof to the independent case. Since for disjoint-path graphs,
CTP can be solved in polynomial time, we examine the complexity of the more
general remote-sensing CTP, and show that it is NP-hard even for disjoint-path
graphs.
