NO
Rewrite Rules:
   [ seteq(?xs,?ys) -> and(subseteq(?xs,?ys),subseteq(?ys,?xs)),
     subseteq(nil,?ys) -> true,
     subseteq(cons(?x,?xs),?ys) -> and(member(?x,?ys),subseteq(?xs,?ys)),
     if(true,?y,?z) -> ?y,
     if(false,?y,?z) -> ?z,
     eq(0,0) -> true,
     eq(0,s(?y)) -> false,
     eq(s(?x),0) -> false,
     eq(s(?x),s(?y)) -> eq(?x,?y),
     member(?x,nil) -> false,
     member(?x,cons(?y,?ys)) -> if(eq(?x,?y),false,member(?x,?ys)),
     and(true,true) -> true,
     and(false,?y) -> false,
     and(?x,false) -> false,
     seteq(?xs,?xs) -> true ]
Apply Direct Methods...
Inner CPs:
   [  ]
Outer CPs:
   [ and(subseteq(?ys,?ys),subseteq(?ys,?ys)) = true,
     false = false ]
Overlay, check Innermost Termination...
Innermost Terminating (hence Terminating), not WCR
Knuth & Bendix
Direct Methods: not CR

Final result: not CR
new/seteq4.trs: Success(not CR)
(24 msec.)