Discrete $(n+1)$-valued states and $n$-perfect pseudo-effect algebras
  We give sufficient and necessary conditions to guarantee that a pseudo-effect algebra admits an $(n+1)$-valued discrete state. We introduce $n$-perfect pseudo-effect algebras as algebras which can be split into $n+1$ comparable slices. We prove that the category of strong $n$-perfect pseudo-effect algebras is categorically equivalent to the category of torsion-free directed partially ordered groups of a special type. 
Anatolij Dvurecenskij, Yongjian Xie, Aili Yang
math.RA