MAYBE

Proof:
ConCon could not decide confluence of the system.
\cite{GNG13}, Theorem 9 does not apply.
System R transformed to optimized U(R).
Call external tool:
csi - trs 30
Input:
  App(App(App(S, x), y), z) -> App(App(x, z), App(y, z))
  App(App(K, x), y) -> x
  App(I, x) -> x
  ?1(y, x, y) -> E
  App(App(D, x), y) -> ?1(x, x, y)

The external tool could not decide confluence.