Loop of length 12 starting with a string of length 9
found after enumerating 160 derivations:

.cbb.bbbbbb
	rule cbb -> bbbcac at position 0
.bbbcac.bbbbbb
	rule cbb -> bbbcac at position 5
.bbbcabbbcac.bbbb
	rule ab ->  at position 4
.bbbcbbcac.bbbb
	rule cbb -> bbbcac at position 8
.bbbcbbcabbbcac.bb
	rule ab ->  at position 7
.bbbcbbcbbcac.bb
	rule cbb -> bbbcac at position 6
.bbbcbbbbbcaccac.bb
	rule cbb -> bbbcac at position 14
.bbbcbbbbbcaccabbbcac.
	rule ab ->  at position 13
.bbbcbbbbbcaccbbcac.
	rule cbb -> bbbcac at position 12
.bbbcbbbbbcacbbbcaccac.
	rule cbb -> bbbcac at position 11
.bbbcbbbbbcabbbcacbcaccac.
	rule ab ->  at position 10
.bbbcbbbbbcbbcacbcaccac.
	rule cbb -> bbbcac at position 9
.bbbcbbbbbbbbcaccacbcaccac.