Loop of length 6 starting with a string of length 6
found after enumerating 32 derivations:

.aaa.baa
	rule aaa -> bba at position 0
.bba.baa
	rule bab -> aba at position 1
.baba.aa
	rule bab -> aba at position 0
.abaa.aa
	rule aaa -> bba at position 3
.ababba.
	rule bab -> aba at position 1
.aababa.
	rule bab -> aba at position 2
.aaabaa.