1 research outputs found
Results in Workflow Resiliency: Complexity, New Formulation, and ASP Encoding
First proposed by Wang and Li in 2007, workflow resiliency is a policy
analysis for ensuring that, even when an adversarial environment removes a
subset of workers from service, a workflow can still be instantiated to satisfy
all the security constraints. Wang and Li proposed three notions of workflow
resiliency: static, decremental, and dynamic resiliency. While decremental and
dynamic resiliency are both PSPACE-complete, Wang and Li did not provide a
matching lower and upper bound for the complexity of static resiliency.
The present work begins with proving that static resiliency is
-complete, thereby bridging a long-standing complexity gap in the
literature. In addition, a fourth notion of workflow resiliency, one-shot
resiliency, is proposed and shown to remain in the third level of the
polynomial hierarchy. This shows that sophisticated notions of workflow
resiliency need not be PSPACE-complete. Lastly, we demonstrate how to reduce
static and one-shot resiliency to Answer Set Programming (ASP), a modern
constraint-solving technology that can be used for solving reasoning tasks in
the lower levels of the polynomial hierarchy. In summary, this work
demonstrates the value of focusing on notions of workflow resiliency that
reside in the lower levels of the polynomial hierarchy