NO
(ignored inputs)COMMENT from p.811 of \cite{Hue80}
Rewrite Rules:
   [ H(H(?x)) -> K(?x) ]
Apply Direct Methods...
Inner CPs:
   [ H(K(?x)) = K(H(?x)) ]
Outer CPs:
   [  ]
not Overlay, check Termination...
Terminating, not WCR
Knuth & Bendix
Direct Methods: not CR

Final result: not CR
44.trs: Success(not CR)
(0 msec.)