a__filter cons X Y 0 M cons 0 filter Y M M a__filter cons X Y s N M cons mark X filter Y N M a__sieve cons 0 Y cons 0 sieve Y a__sieve cons s N Y cons s mark N sieve filter Y N N a__nats N cons mark N nats s N a__zprimes a__sieve a__nats s s 0 mark filter X1 X2 X3 a__filter mark X1 mark X2 mark X3 mark sieve X a__sieve mark X mark nats X a__nats mark X mark zprimes a__zprimes mark cons X1 X2 cons mark X1 X2 mark 0 0 mark s X s mark X a__filter X1 X2 X3 filter X1 X2 X3 a__sieve X sieve X a__nats X nats X a__zprimes zprimes 2.2 a__zprimes a__sieve a__nats s s 0 mark nats X mark X a__nats N mark N mark filter X1 X2 X3 mark X1 mark filter X1 X2 X3 mark X3 mark zprimes a__zprimes mark sieve X a__sieve mark X mark cons X1 X2 mark X1 mark filter X1 X2 X3 mark X2 mark nats X a__nats mark X a__sieve cons s N Y mark N a__zprimes a__nats s s 0 a__filter cons X Y s N M mark X mark filter X1 X2 X3 a__filter mark X1 mark X2 mark X3 mark sieve X mark X mark s X mark X true mark s X mark X mark sieve X a__sieve mark X mark sieve X mark X mark zprimes a__zprimes mark filter X1 X2 X3 a__filter mark X1 mark X2 mark X3 a__filter cons X Y s N M mark X a__zprimes a__nats s s 0 a__sieve cons s N Y mark N mark filter X1 X2 X3 mark X3 mark filter X1 X2 X3 mark X1 a__nats N mark N mark nats X mark X mark nats X a__nats mark X mark filter X1 X2 X3 mark X2 mark cons X1 X2 mark X1 a__zprimes a__sieve a__nats s s 0 true zprimes 0 23681 s 1 1 1 a__zprimes 0 23681 a__nats 1 1 2 a__filter 3 1 3 1 a__sieve 1 1 1 a__zprimes 0 23681 mark 1 1 1 0 0 23676 a__nats 1 1 2 mark 1 1 0 sieve 1 1 1 nats 1 1 2 cons 2 1 1 filter 3 1 2 3 4 a__sieve 1 1 0 a__filter 3 1 2 3 4 a__sieve cons s N Y cons s mark N sieve filter Y N N a__sieve X sieve X mark sieve X a__sieve mark X a__filter cons X Y 0 M cons 0 filter Y M M a__sieve cons 0 Y cons 0 sieve Y a__nats X nats X a__zprimes zprimes a__nats N cons mark N nats s N mark zprimes a__zprimes mark filter X1 X2 X3 a__filter mark X1 mark X2 mark X3 a__filter X1 X2 X3 filter X1 X2 X3 mark 0 0 mark cons X1 X2 cons mark X1 X2 mark nats X a__nats mark X mark s X s mark X a__zprimes a__sieve a__nats s s 0 a__filter cons X Y s N M cons mark X filter Y N M NaTT certifiable-1.6