YES
exiting with thread!
(VAR x y z )
(RULES 
        +(0,x) -> x
        +(s(x),y) -> s(+(x,y))
        +(+(x,y),z) -> +(x,+(y,z))
        fib(0) -> 0
        fib(s(0)) -> s(0)
        fib(s(s(x))) -> +(fib(x),fib(s(x)))
        dfib(0,y) -> y
        dfib(s(0),y) -> s(y)
        dfib(s(s(x)),y) -> dfib(s(x),dfib(x,y))
        
)