Loop of length 15 starting with a string of length 12
found after enumerating 2923 derivations:

.aaaa.abababaa
	rule aaaa -> abba at position 0
.abba.abababaa
	rule baab -> aaba at position 2
.abaaba.ababaa
	rule baab -> aaba at position 4
.abaaaaba.abaa
	rule baab -> aaba at position 6
.abaaaaaaba.aa
	rule aaaa -> abba at position 3
.abaabbaaba.aa
	rule baab -> aaba at position 5
.abaabaabaa.aa
	rule baab -> aaba at position 4
.abaaaabaaa.aa
	rule aaaa -> abba at position 8
.abaaaabaabba.
	rule baab -> aaba at position 6
.abaaaaaababa.
	rule aaaa -> abba at position 3
.abaabbaababa.
	rule baab -> aaba at position 1
.aaababaababa.
	rule baab -> aaba at position 5
.aaabaaabaaba.
	rule baab -> aaba at position 7
.aaabaaaaabaa.
	rule aaaa -> abba at position 5
.aaabaabbabaa.
	rule baab -> aaba at position 3
.aaaaabababaa.