A Short Mechanized Proof of the Church-Rosser Theorem by the Z-property   for the $\lambda\beta$-calculus in Nominal Isabelle
  We present a short proof of the Church-Rosser property for the lambda-calculus enjoying two distinguishing features: Firstly, it employs the Z-property, resulting in a short and elegant proof; and secondly, it is formalized in the nominal higher-order logic available for the proof assistant Isabelle/HOL. 
Julian Nagele, Vincent van Oostrom, Christian Sternagel
cs.LO