YES(?,O(n^1)) Problem: rec(rec(x)) -> sent(rec(x)) rec(sent(x)) -> sent(rec(x)) rec(no(x)) -> sent(rec(x)) rec(bot()) -> up(sent(bot())) rec(up(x)) -> up(rec(x)) sent(up(x)) -> up(sent(x)) no(up(x)) -> up(no(x)) top(rec(up(x))) -> top(check(rec(x))) top(sent(up(x))) -> top(check(rec(x))) top(no(up(x))) -> top(check(rec(x))) check(up(x)) -> up(check(x)) check(sent(x)) -> sent(check(x)) check(rec(x)) -> rec(check(x)) check(no(x)) -> no(check(x)) check(no(x)) -> no(x) Proof: Bounds Processor: bound: 1 enrichment: match automaton: final states: {7,6,5,4,3} transitions: up1(9) -> 10* up1(46) -> 47* up1(36) -> 37* up1(26) -> 27* check1(45) -> 46* check1(48) -> 49* no1(35) -> 36* no1(38) -> 39* sent1(25) -> 26* sent1(28) -> 29* sent1(8) -> 9* rec1(16) -> 17* rec1(18) -> 19* bot1() -> 8* rec0(2) -> 3* rec0(1) -> 3* sent0(2) -> 4* sent0(1) -> 4* no0(2) -> 5* no0(1) -> 5* bot0() -> 1* up0(2) -> 2* up0(1) -> 2* top0(2) -> 6* top0(1) -> 6* check0(2) -> 7* check0(1) -> 7* 1 -> 48,38,28,18 2 -> 45,35,25,16 10 -> 17,19,9,3 17 -> 9* 19 -> 9* 27 -> 26,4 29 -> 26* 37 -> 36,5 39 -> 36* 47 -> 46,7 49 -> 46* problem: Qed