(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)) mark(fib(X)) -> active(fib(mark(X))) mark(sel(X1,X2)) -> active(sel(mark(X1),mark(X2))) mark(fib1(X1,X2)) -> active(fib1(mark(X1),mark(X2))) mark(s(X)) -> active(s(mark(X))) mark(0) -> active(0) mark(cons(X1,X2)) -> active(cons(mark(X1),X2)) mark(add(X1,X2)) -> active(add(mark(X1),mark(X2))) fib(mark(X)) -> fib(X) fib(active(X)) -> fib(X) sel(mark(X1),X2) -> sel(X1,X2) sel(X1,mark(X2)) -> sel(X1,X2) sel(active(X1),X2) -> sel(X1,X2) sel(X1,active(X2)) -> sel(X1,X2) fib1(mark(X1),X2) -> fib1(X1,X2) fib1(X1,mark(X2)) -> fib1(X1,X2) fib1(active(X1),X2) -> fib1(X1,X2) fib1(X1,active(X2)) -> fib1(X1,X2) s(mark(X)) -> s(X) s(active(X)) -> s(X) cons(mark(X1),X2) -> cons(X1,X2) cons(X1,mark(X2)) -> cons(X1,X2) cons(active(X1),X2) -> cons(X1,X2) cons(X1,active(X2)) -> cons(X1,X2) add(mark(X1),X2) -> add(X1,X2) add(X1,mark(X2)) -> add(X1,X2) add(active(X1),X2) -> add(X1,X2) add(X1,active(X2)) -> add(X1,X2) )