Service Level Agreement Complexity: Processing Concerns for Standalone   and Aggregate SLAs
  In this paper, we examine the problem of a single provider offering multiple types of service level agreements, and the implications thereof. In doing so, we propose a simple model for machine-readable service level agreements (SLAs) and outline specifically how these machine-readable SLAs can be constructed and injected into cloud infrastructures - important for next-generation cloud systems as well as customers. We then computationally characterize the problem, establishing the importance of both verification and solution, showing that in the general case injecting policies into cloud infrastructure is NP-Complete, though the problem can be made more tractable by further constraining SLA representations and using approximation techniques. 
Christopher C. Lamb, Gregory L. Heileman
cs.SE