Abstract
While it is easy to verify that an action sequence
is a solution for a classical planning task, there is
no such verification capability if a task is reported
unsolvable. We are therefore interested in certifi-
cates that allow an independent verification of the
absence of solutions. We identify promising concepts for certificates that can be generated by a wide
range of planning approaches. We present a first
proposal of unsolvability certificates and sketch
ideas how the underlying concepts can be used as
part of a more flexible unsolvability proof system