We are left with following problem, upon which TcT provides the certificate YES(?,O(n^1)). Strict Trs: { active(nats()) -> mark(adx(zeros())) , active(adx(X)) -> adx(active(X)) , active(adx(cons(X, Y))) -> mark(incr(cons(X, adx(Y)))) , active(zeros()) -> mark(cons(0(), zeros())) , active(incr(X)) -> incr(active(X)) , active(incr(cons(X, Y))) -> mark(cons(s(X), incr(Y))) , active(hd(X)) -> hd(active(X)) , active(hd(cons(X, Y))) -> mark(X) , active(tl(X)) -> tl(active(X)) , active(tl(cons(X, Y))) -> mark(Y) , adx(mark(X)) -> mark(adx(X)) , adx(ok(X)) -> ok(adx(X)) , cons(ok(X1), ok(X2)) -> ok(cons(X1, X2)) , incr(mark(X)) -> mark(incr(X)) , incr(ok(X)) -> ok(incr(X)) , s(ok(X)) -> ok(s(X)) , hd(mark(X)) -> mark(hd(X)) , hd(ok(X)) -> ok(hd(X)) , tl(mark(X)) -> mark(tl(X)) , tl(ok(X)) -> ok(tl(X)) , proper(nats()) -> ok(nats()) , proper(adx(X)) -> adx(proper(X)) , proper(zeros()) -> ok(zeros()) , proper(cons(X1, X2)) -> cons(proper(X1), proper(X2)) , proper(0()) -> ok(0()) , proper(incr(X)) -> incr(proper(X)) , proper(s(X)) -> s(proper(X)) , proper(hd(X)) -> hd(proper(X)) , proper(tl(X)) -> tl(proper(X)) , top(mark(X)) -> top(proper(X)) , top(ok(X)) -> top(active(X)) } Obligation: innermost runtime complexity Answer: YES(?,O(n^1)) The problem is match-bounded by 10. The enriched problem is compatible with the following automaton. { active_0(2) -> 1 , active_0(3) -> 1 , active_0(5) -> 1 , active_0(7) -> 1 , active_0(13) -> 1 , active_1(2) -> 25 , active_1(3) -> 25 , active_1(5) -> 25 , active_1(7) -> 25 , active_1(13) -> 25 , active_2(16) -> 26 , active_2(17) -> 26 , active_2(24) -> 26 , active_3(33) -> 32 , active_4(28) -> 38 , active_4(41) -> 42 , active_5(35) -> 43 , active_5(57) -> 50 , active_6(55) -> 51 , active_6(62) -> 63 , active_7(58) -> 64 , active_7(79) -> 69 , active_8(78) -> 72 , active_8(87) -> 88 , active_9(86) -> 89 , active_9(107) -> 96 , active_10(110) -> 111 , nats_0() -> 2 , nats_1() -> 24 , mark_0(2) -> 3 , mark_0(3) -> 3 , mark_0(5) -> 3 , mark_0(7) -> 3 , mark_0(13) -> 3 , mark_1(15) -> 1 , mark_1(15) -> 25 , mark_1(18) -> 4 , mark_1(18) -> 18 , mark_1(20) -> 8 , mark_1(20) -> 20 , mark_1(22) -> 10 , mark_1(22) -> 22 , mark_1(23) -> 11 , mark_1(23) -> 23 , mark_2(27) -> 26 , mark_3(39) -> 38 , mark_4(40) -> 32 , mark_4(44) -> 43 , mark_5(47) -> 42 , mark_6(59) -> 50 , mark_7(65) -> 63 , mark_7(82) -> 69 , mark_8(90) -> 88 , adx_0(2) -> 4 , adx_0(3) -> 4 , adx_0(5) -> 4 , adx_0(7) -> 4 , adx_0(13) -> 4 , adx_1(2) -> 18 , adx_1(3) -> 18 , adx_1(5) -> 18 , adx_1(7) -> 18 , adx_1(13) -> 18 , adx_1(16) -> 15 , adx_2(28) -> 27 , adx_2(30) -> 26 , adx_3(28) -> 33 , adx_3(34) -> 32 , adx_4(35) -> 41 , adx_4(38) -> 32 , adx_4(39) -> 40 , adx_5(43) -> 42 , adx_5(44) -> 47 , adx_6(46) -> 61 , adx_6(51) -> 50 , adx_6(55) -> 57 , adx_6(56) -> 77 , adx_7(56) -> 67 , adx_7(58) -> 62 , adx_7(64) -> 63 , adx_7(73) -> 71 , adx_7(81) -> 85 , adx_7(98) -> 95 , adx_8(80) -> 75 , adx_8(103) -> 101 , adx_8(104) -> 106 , zeros_0() -> 5 , zeros_1() -> 16 , zeros_2() -> 28 , zeros_3() -> 35 , zeros_4() -> 46 , zeros_5() -> 56 , zeros_6() -> 81 , zeros_7() -> 104 , cons_0(2, 2) -> 6 , cons_0(2, 3) -> 6 , cons_0(2, 5) -> 6 , cons_0(2, 7) -> 6 , cons_0(2, 13) -> 6 , cons_0(3, 2) -> 6 , cons_0(3, 3) -> 6 , cons_0(3, 5) -> 6 , cons_0(3, 7) -> 6 , cons_0(3, 13) -> 6 , cons_0(5, 2) -> 6 , cons_0(5, 3) -> 6 , cons_0(5, 5) -> 6 , cons_0(5, 7) -> 6 , cons_0(5, 13) -> 6 , cons_0(7, 2) -> 6 , cons_0(7, 3) -> 6 , cons_0(7, 5) -> 6 , cons_0(7, 7) -> 6 , cons_0(7, 13) -> 6 , cons_0(13, 2) -> 6 , cons_0(13, 3) -> 6 , cons_0(13, 5) -> 6 , cons_0(13, 7) -> 6 , cons_0(13, 13) -> 6 , cons_1(2, 2) -> 19 , cons_1(2, 3) -> 19 , cons_1(2, 5) -> 19 , cons_1(2, 7) -> 19 , cons_1(2, 13) -> 19 , cons_1(3, 2) -> 19 , cons_1(3, 3) -> 19 , cons_1(3, 5) -> 19 , cons_1(3, 7) -> 19 , cons_1(3, 13) -> 19 , cons_1(5, 2) -> 19 , cons_1(5, 3) -> 19 , cons_1(5, 5) -> 19 , cons_1(5, 7) -> 19 , cons_1(5, 13) -> 19 , cons_1(7, 2) -> 19 , cons_1(7, 3) -> 19 , cons_1(7, 5) -> 19 , cons_1(7, 7) -> 19 , cons_1(7, 13) -> 19 , cons_1(13, 2) -> 19 , cons_1(13, 3) -> 19 , cons_1(13, 5) -> 19 , cons_1(13, 7) -> 19 , cons_1(13, 13) -> 19 , cons_1(17, 16) -> 15 , cons_2(29, 28) -> 27 , cons_2(31, 30) -> 26 , cons_3(29, 28) -> 33 , cons_3(36, 34) -> 32 , cons_3(37, 35) -> 39 , cons_4(37, 35) -> 41 , cons_4(45, 46) -> 44 , cons_4(48, 49) -> 43 , cons_5(45, 46) -> 55 , cons_5(52, 53) -> 51 , cons_6(45, 61) -> 60 , cons_6(54, 56) -> 58 , cons_6(54, 77) -> 78 , cons_7(54, 67) -> 66 , cons_7(70, 71) -> 68 , cons_7(76, 85) -> 86 , cons_7(83, 84) -> 82 , cons_8(74, 75) -> 72 , cons_8(91, 92) -> 90 , cons_8(93, 94) -> 88 , cons_8(97, 92) -> 107 , cons_9(99, 100) -> 96 , cons_9(109, 108) -> 110 , 0_0() -> 7 , 0_1() -> 17 , 0_2() -> 29 , 0_3() -> 37 , 0_4() -> 45 , 0_5() -> 54 , 0_6() -> 76 , 0_7() -> 105 , incr_0(2) -> 8 , incr_0(3) -> 8 , incr_0(5) -> 8 , incr_0(7) -> 8 , incr_0(13) -> 8 , incr_1(2) -> 20 , incr_1(3) -> 20 , incr_1(5) -> 20 , incr_1(7) -> 20 , incr_1(13) -> 20 , incr_6(60) -> 59 , incr_7(66) -> 65 , incr_7(68) -> 63 , incr_7(77) -> 84 , incr_7(78) -> 79 , incr_8(72) -> 69 , incr_8(85) -> 92 , incr_8(86) -> 87 , incr_8(95) -> 94 , incr_9(89) -> 88 , incr_9(101) -> 100 , incr_9(106) -> 108 , s_0(2) -> 9 , s_0(3) -> 9 , s_0(5) -> 9 , s_0(7) -> 9 , s_0(13) -> 9 , s_1(2) -> 21 , s_1(3) -> 21 , s_1(5) -> 21 , s_1(7) -> 21 , s_1(13) -> 21 , s_7(54) -> 83 , s_7(76) -> 97 , s_8(74) -> 93 , s_8(76) -> 91 , s_8(105) -> 109 , s_9(102) -> 99 , hd_0(2) -> 10 , hd_0(3) -> 10 , hd_0(5) -> 10 , hd_0(7) -> 10 , hd_0(13) -> 10 , hd_1(2) -> 22 , hd_1(3) -> 22 , hd_1(5) -> 22 , hd_1(7) -> 22 , hd_1(13) -> 22 , tl_0(2) -> 11 , tl_0(3) -> 11 , tl_0(5) -> 11 , tl_0(7) -> 11 , tl_0(13) -> 11 , tl_1(2) -> 23 , tl_1(3) -> 23 , tl_1(5) -> 23 , tl_1(7) -> 23 , tl_1(13) -> 23 , proper_0(2) -> 12 , proper_0(3) -> 12 , proper_0(5) -> 12 , proper_0(7) -> 12 , proper_0(13) -> 12 , proper_1(2) -> 25 , proper_1(3) -> 25 , proper_1(5) -> 25 , proper_1(7) -> 25 , proper_1(13) -> 25 , proper_2(15) -> 26 , proper_2(16) -> 30 , proper_2(17) -> 31 , proper_3(27) -> 32 , proper_3(28) -> 34 , proper_3(29) -> 36 , proper_4(35) -> 49 , proper_4(37) -> 48 , proper_4(40) -> 42 , proper_5(39) -> 43 , proper_5(45) -> 52 , proper_5(46) -> 53 , proper_5(47) -> 50 , proper_6(44) -> 51 , proper_6(59) -> 63 , proper_7(45) -> 70 , proper_7(46) -> 73 , proper_7(56) -> 98 , proper_7(60) -> 68 , proper_7(61) -> 71 , proper_7(65) -> 69 , proper_8(54) -> 74 , proper_8(56) -> 80 , proper_8(66) -> 72 , proper_8(67) -> 75 , proper_8(77) -> 95 , proper_8(81) -> 103 , proper_8(82) -> 88 , proper_8(83) -> 93 , proper_8(84) -> 94 , proper_9(76) -> 102 , proper_9(85) -> 101 , proper_9(90) -> 96 , proper_9(91) -> 99 , proper_9(92) -> 100 , ok_0(2) -> 13 , ok_0(3) -> 13 , ok_0(5) -> 13 , ok_0(7) -> 13 , ok_0(13) -> 13 , ok_1(16) -> 12 , ok_1(16) -> 25 , ok_1(17) -> 12 , ok_1(17) -> 25 , ok_1(18) -> 4 , ok_1(18) -> 18 , ok_1(19) -> 6 , ok_1(19) -> 19 , ok_1(20) -> 8 , ok_1(20) -> 20 , ok_1(21) -> 9 , ok_1(21) -> 21 , ok_1(22) -> 10 , ok_1(22) -> 22 , ok_1(23) -> 11 , ok_1(23) -> 23 , ok_1(24) -> 12 , ok_1(24) -> 25 , ok_2(28) -> 30 , ok_2(29) -> 31 , ok_3(33) -> 26 , ok_3(35) -> 34 , ok_3(37) -> 36 , ok_4(41) -> 32 , ok_4(45) -> 48 , ok_4(46) -> 49 , ok_5(54) -> 52 , ok_5(54) -> 70 , ok_5(55) -> 43 , ok_5(56) -> 53 , ok_5(56) -> 73 , ok_6(57) -> 42 , ok_6(58) -> 51 , ok_6(76) -> 74 , ok_6(77) -> 71 , ok_6(78) -> 68 , ok_6(81) -> 80 , ok_6(81) -> 98 , ok_7(62) -> 50 , ok_7(79) -> 63 , ok_7(85) -> 75 , ok_7(85) -> 95 , ok_7(86) -> 72 , ok_7(97) -> 93 , ok_7(104) -> 103 , ok_7(105) -> 102 , ok_8(87) -> 69 , ok_8(92) -> 94 , ok_8(106) -> 101 , ok_8(107) -> 88 , ok_8(109) -> 99 , ok_9(108) -> 100 , ok_9(110) -> 96 , top_0(2) -> 14 , top_0(3) -> 14 , top_0(5) -> 14 , top_0(7) -> 14 , top_0(13) -> 14 , top_1(25) -> 14 , top_2(26) -> 14 , top_3(32) -> 14 , top_4(42) -> 14 , top_5(50) -> 14 , top_6(63) -> 14 , top_7(69) -> 14 , top_8(88) -> 14 , top_9(96) -> 14 , top_10(111) -> 14 } Hurray, we answered YES(?,O(n^1))