your answer does not contain all solutions

[lxhao]

hello!
your answer is :
<(D,)>. <(A,)>. <(B,)>. <(F,)>.
<(D,)(A,)>. <(D,)(B,)>. <(D,)(F,)>. <(D,)(B,)(A,)>. <(D,)(F,)(A,)>. <(D,)(B,F,)>. <(A,B,)>. <(B,)(A,)>. <(A,F,)>. <(F,)(A,)>. <(B,F,)>

I get the answer from book include other sequences besides yours , such as:
<(D,)(B,F)(A,)>. <(A,B,F)>. <(B,F)(A)>

[magdamagda]

hello,
I found the mistake, it should be better now.