Loop of length 12 starting with a string of length 6
found after enumerating 2142 derivations:

.cb.bbbb
	rule cb -> babc at position 0
.babc.bbbb
	rule b ->  at position 2
.bac.bbbb
	rule cb -> babc at position 2
.bababc.bbb
	rule b ->  at position 2
.baabc.bbb
	rule b ->  at position 3
.baac.bbb
	rule cb -> babc at position 3
.baababc.bb
	rule b ->  at position 3
.baaabc.bb
	rule aaa -> c at position 1
.bcbc.bb
	rule cb -> babc at position 3
.bcbbabc.b
	rule a ->  at position 4
.bcbbbc.b
	rule cb -> babc at position 5
.bcbbbbabc.
	rule a ->  at position 6
.bcbbbbbc.