4.21/1.92	YES
4.21/1.92	
4.21/1.92	Proof:
4.21/1.92	This system is confluent.
4.21/1.92	By \cite{GNG13}, Theorem 9.
4.21/1.92	This system is of type 3 or smaller.
4.21/1.92	This system is deterministic.
4.21/1.92	This system is weakly left-linear.
4.21/1.92	System R transformed to optimized U(R).
4.21/1.92	This system is orthogonal.
4.21/1.92	
6.57/2.51	EOF