(VAR N X Y XS X1 X2)
(RULES 
active(fib(N)) -> mark(sel(N,fib1(s(0),s(0))))
active(fib1(X,Y)) -> mark(cons(X,fib1(Y,add(X,Y))))
active(add(0,X)) -> mark(X)
active(add(s(X),Y)) -> mark(s(add(X,Y)))
active(sel(0,cons(X,XS))) -> mark(X)
active(sel(s(N),cons(X,XS))) -> mark(sel(N,XS))
active(fib(X)) -> fib(active(X))
active(sel(X1,X2)) -> sel(active(X1),X2)
active(sel(X1,X2)) -> sel(X1,active(X2))
active(fib1(X1,X2)) -> fib1(active(X1),X2)
active(fib1(X1,X2)) -> fib1(X1,active(X2))
active(s(X)) -> s(active(X))
active(cons(X1,X2)) -> cons(active(X1),X2)
active(add(X1,X2)) -> add(active(X1),X2)
active(add(X1,X2)) -> add(X1,active(X2))
fib(mark(X)) -> mark(fib(X))
sel(mark(X1),X2) -> mark(sel(X1,X2))
sel(X1,mark(X2)) -> mark(sel(X1,X2))
fib1(mark(X1),X2) -> mark(fib1(X1,X2))
fib1(X1,mark(X2)) -> mark(fib1(X1,X2))
s(mark(X)) -> mark(s(X))
cons(mark(X1),X2) -> mark(cons(X1,X2))
add(mark(X1),X2) -> mark(add(X1,X2))
add(X1,mark(X2)) -> mark(add(X1,X2))
proper(fib(X)) -> fib(proper(X))
proper(sel(X1,X2)) -> sel(proper(X1),proper(X2))
proper(fib1(X1,X2)) -> fib1(proper(X1),proper(X2))
proper(s(X)) -> s(proper(X))
proper(0) -> ok(0)
proper(cons(X1,X2)) -> cons(proper(X1),proper(X2))
proper(add(X1,X2)) -> add(proper(X1),proper(X2))
fib(ok(X)) -> ok(fib(X))
sel(ok(X1),ok(X2)) -> ok(sel(X1,X2))
fib1(ok(X1),ok(X2)) -> ok(fib1(X1,X2))
s(ok(X)) -> ok(s(X))
cons(ok(X1),ok(X2)) -> ok(cons(X1,X2))
add(ok(X1),ok(X2)) -> ok(add(X1,X2))
top(mark(X)) -> top(proper(X))
top(ok(X)) -> top(active(X))
)