Loop of length 25 starting with a string of length 11
found after enumerating 447 derivations:

.aaaa.baabbba
	rule aaaa -> bbba at position 0
.bbba.baabbba
	rule bbab -> abaa at position 1
.babaa.aabbba
	rule aaaa -> bbba at position 3
.babbbba.bbba
	rule bbab -> abaa at position 4
.babbabaa.bba
	rule bbab -> abaa at position 2
.baabaaaa.bba
	rule aaaa -> bbba at position 4
.baabbbba.bba
	rule bbab -> abaa at position 5
.baabbabaa.ba
	rule bbab -> abaa at position 3
.baaabaaaa.ba
	rule aaaa -> bbba at position 5
.baaabbbba.ba
	rule bbab -> abaa at position 6
.baaabbabaa.a
	rule bbab -> abaa at position 4
.baaaabaaaa.a
	rule aaaa -> bbba at position 1
.bbbbabaaaa.a
	rule bbab -> abaa at position 2
.bbabaaaaaa.a
	rule bbab -> abaa at position 0
.abaaaaaaaa.a
	rule aaaa -> bbba at position 2
.abbbbaaaaa.a
	rule aaaa -> bbba at position 6
.abbbbabbba.a
	rule bbab -> abaa at position 3
.abbabaabba.a
	rule bbab -> abaa at position 1
.aabaaaabba.a
	rule aaaa -> bbba at position 3
.aabbbbabba.a
	rule bbab -> abaa at position 4
.aabbabaaba.a
	rule bbab -> abaa at position 2
.aaabaaaaba.a
	rule aaaa -> bbba at position 4
.aaabbbbaba.a
	rule bbab -> abaa at position 5
.aaabbabaaa.a
	rule bbab -> abaa at position 3
.aaaabaaaaa.a
	rule aaaa -> bbba at position 7
.aaaabaabbba.