NO
Rewrite Rules:
   [ seteq(?xs,?ys) -> and(subseteq(?xs,?ys),subseteq(?ys,?xs)),
     subseteq(nil,nil) -> true,
     subseteq(nil,cons(?y,?ys)) -> false,
     subseteq(cons(?x,?xs),?ys) -> and(member(?x,?ys),subseteq(?xs,?ys)),
     member(?x,nil) -> false,
     member(?x,cons(?y,?ys)) -> or(eq(?x,?y),member(?x,?ys)),
     eq(0,0) -> true,
     eq(0,s(?y)) -> false,
     eq(s(?x),0) -> false,
     eq(s(?x),s(?y)) -> eq(?x,?y),
     or(?x,true) -> true,
     or(true,?y) -> true,
     or(false,false) -> false,
     and(true,true) -> true,
     and(?x,false) -> false,
     and(false,?y) -> false,
     app(nil,?ys) -> ?ys,
     app(cons(?x,?xs),?ys) -> cons(?x,app(?xs,?ys)),
     seteq(app(?xs,?ys),app(?ys,?xs)) -> true ]
Apply Direct Methods...
Inner CPs:
   [ seteq(?ys_12,app(?ys_12,nil)) = true,
     seteq(app(?ys_12,nil),?ys_12) = true,
     seteq(cons(?x_13,app(?xs_13,?ys_13)),app(?ys_13,cons(?x_13,?xs_13))) = true,
     seteq(app(?ys_13,cons(?x_13,?xs_13)),cons(?x_13,app(?xs_13,?ys_13))) = true ]
Outer CPs:
   [ and(subseteq(app(?xs_14,?ys_14),app(?ys_14,?xs_14)),subseteq(app(?ys_14,?xs_14),app(?xs_14,?ys_14))) = true,
     true = true,
     false = false ]
not Overlay, check Termination...
Terminating, not WCR
Knuth & Bendix
Direct Methods: not CR

Final result: not CR
new/seteq2.trs: Success(not CR)
(29 msec.)