Loop of length 8 starting with a string of length 6
found after enumerating 3676 derivations:

.a.abbbb
	rule a -> c at position 0
.c.abbbb
	rule cab -> bbaca at position 0
.bbaca.bbb
	rule cab -> bbaca at position 3
.bbabbaca.bb
	rule b ->  at position 3
.bbabaca.bb
	rule b ->  at position 3
.bbaaca.bb
	rule cab -> bbaca at position 4
.bbaabbaca.b
	rule a ->  at position 6
.bbaabbca.b
	rule cab -> bbaca at position 6
.bbaabbbbaca.