Loop of length 13 starting with a string of length 6
found after enumerating 11880 derivations:

.ba.aaca
	rule ba -> abcb at position 0
.abcb.aaca
	rule ba -> abcb at position 3
.abcabcb.aca
	rule a ->  at position 3
.abcbcb.aca
	rule b -> a at position 3
.abcacb.aca
	rule a ->  at position 3
.abccb.aca
	rule cc ->  at position 2
.abb.aca
	rule ba -> abcb at position 2
.ababcb.ca
	rule b -> a at position 5
.ababca.ca
	rule a ->  at position 5
.ababc.ca
	rule cc ->  at position 4
.abab.a
	rule ba -> abcb at position 3
.abaabcb.
	rule b -> a at position 4
.abaaacb.
	rule b -> a at position 6
.abaaaca.