YES
(ignored inputs)COMMENT doi:10.1017/CBO9781139172752 [4] Exercise 6.17 submitted by: Takahito Aoto , Junichi Yoshida , and Yoshihito Toyama
Rewrite Rules:
   [ or(true,true) -> true,
     or(?x,?y) -> or(?y,?x) ]
Apply Direct Methods...
Inner CPs:
   [  ]
Outer CPs:
   [ true = or(true,true) ]
Overlay, check Innermost Termination...
unknown Innermost Terminating
unknown Knuth & Bendix
Linear
Development Closed
Direct Methods: CR

Combined result: CR
4.trs: Success(CR)
(0 msec.)