Title:The Boundary between Decidable and Undecidable Fragments 
      of the Fluent Calculus

Authors: Steffen Hoelldobler, Dietrich Kuske 

Abstract:

We consider decision problems in the fluent calculus as they
arise in reasoning about actions. Taking into account various
fragments of the fluent calculus we formally show decidability
results, establish their complexity, and prove undecidability
results. This allows us to draw a boundary between decidable and
undecidable fragments of the fluent calculus.