(VAR X Y Z X1 X2 X3) (RULES a__primes -> a__sieve(a__from(s(s(0)))) a__from(X) -> cons(mark(X),from(s(X))) a__head(cons(X,Y)) -> mark(X) a__tail(cons(X,Y)) -> mark(Y) a__if(true,X,Y) -> mark(X) a__if(false,X,Y) -> mark(Y) a__filter(s(s(X)),cons(Y,Z)) -> a__if(divides(s(s(mark(X))),mark(Y)),filter(s(s(X)),Z),cons(Y,filter(X,sieve(Y)))) a__sieve(cons(X,Y)) -> cons(mark(X),filter(X,sieve(Y))) mark(primes) -> a__primes mark(sieve(X)) -> a__sieve(mark(X)) mark(from(X)) -> a__from(mark(X)) mark(head(X)) -> a__head(mark(X)) mark(tail(X)) -> a__tail(mark(X)) mark(if(X1,X2,X3)) -> a__if(mark(X1),X2,X3) mark(filter(X1,X2)) -> a__filter(mark(X1),mark(X2)) mark(s(X)) -> s(mark(X)) mark(0) -> 0 mark(cons(X1,X2)) -> cons(mark(X1),X2) mark(true) -> true mark(false) -> false mark(divides(X1,X2)) -> divides(mark(X1),mark(X2)) a__primes -> primes a__sieve(X) -> sieve(X) a__from(X) -> from(X) a__head(X) -> head(X) a__tail(X) -> tail(X) a__if(X1,X2,X3) -> if(X1,X2,X3) a__filter(X1,X2) -> filter(X1,X2) )