Loop of length 30 starting with a string of length 8
found after enumerating 1941 derivations:

.bc.cccccc
	rule bc -> ab at position 0
.ab.cccccc
	rule bc -> ab at position 1
.aab.ccccc
	rule bc -> ab at position 2
.aaab.cccc
	rule bc -> ab at position 3
.aaaab.ccc
	rule bc -> ab at position 4
.aaaaab.cc
	rule bc -> ab at position 5
.aaaaaab.c
	rule ab ->  at position 5
.aaaaa.c
	rule ac -> cccb at position 4
.aaaacccb.
	rule ac -> cccb at position 3
.aaacccbccb.
	rule ac -> cccb at position 2
.aacccbccbccb.
	rule ac -> cccb at position 1
.acccbccbccbccb.
	rule ac -> cccb at position 0
.cccbccbccbccbccb.
	rule bc -> ab at position 6
.cccbccabcbccbccb.
	rule bc -> ab at position 7
.cccbccaabbccbccb.
	rule bc -> ab at position 9
.cccbccaababcbccb.
	rule bc -> ab at position 10
.cccbccaabaabbccb.
	rule ab ->  at position 10
.cccbccaababccb.
	rule bc -> ab at position 10
.cccbccaabaabcb.
	rule ab ->  at position 10
.cccbccaabacb.
	rule ac -> cccb at position 9
.cccbccaabcccbb.
	rule bc -> ab at position 8
.cccbccaaabccbb.
	rule bc -> ab at position 9
.cccbccaaaabcbb.
	rule ab ->  at position 9
.cccbccaaacbb.
	rule ac -> cccb at position 8
.cccbccaacccbbb.
	rule ac -> cccb at position 7
.cccbccacccbccbbb.
	rule ac -> cccb at position 6
.cccbcccccbccbccbbb.
	rule bc -> ab at position 9
.cccbcccccabcbccbbb.
	rule ab ->  at position 9
.cccbccccccbccbbb.
	rule bc -> ab at position 10
.cccbccccccabcbbb.
	rule ab ->  at position 10
.cccbcccccccbbb.