Quantum Observables and Effect Algebras
  We study observables on monotone $\sigma$-complete effect algebras. We find conditions when a spectral resolution implies existence of the corresponding observable. The set of sharp elements of a monotone $\sigma$-complete homogeneous effect algebra is a monotone $\sigma$-complete subalgebra. In addition, we study compatibility in orthoalgebras. 
Anatolij Dvure\v{c}enskij
math-ph math.MP math.RA