Loop of length 16 starting with a string of length 8
found after enumerating 373 derivations:

.ab.bbbbbb
	rule ab -> bc at position 0
.bc.bbbbbb
	rule cbb -> bbacb at position 1
.bbbacb.bbbb
	rule cbb -> bbacb at position 4
.bbbabbacb.bbb
	rule cbb -> bbacb at position 7
.bbbabbabbacb.bb
	rule ab -> bc at position 6
.bbbabbbcbacb.bb
	rule cbb -> bbacb at position 10
.bbbabbbcbabbacb.b
	rule ab -> bc at position 9
.bbbabbbcbbcbacb.b
	rule cbb -> bbacb at position 7
.bbbabbbbbacbcbacb.b
	rule cbb -> bbacb at position 15
.bbbabbbbbacbcbabbacb.
	rule ab -> bc at position 14
.bbbabbbbbacbcbbcbacb.
	rule cbb -> bbacb at position 12
.bbbabbbbbacbbbacbcbacb.
	rule cbb -> bbacb at position 10
.bbbabbbbbabbacbbacbcbacb.
	rule ab -> bc at position 9
.bbbabbbbbbcbacbbacbcbacb.
	rule cbb -> bbacb at position 13
.bbbabbbbbbcbabbacbacbcbacb.
	rule ab -> bc at position 12
.bbbabbbbbbcbbcbacbacbcbacb.
	rule cbb -> bbacb at position 10
.bbbabbbbbbbbacbcbacbacbcbacb.