Is this a valid DFA for (a|b)*abb? I'm trying to come up with an alternate DFA for accepting (a|b)*abb than the one present in the dragon book. Here's the one I tried:



It seems valid to me but I'm not sure. Also, is there a way to check for validity of automatons so that I don't end up bugging you guys next time?
Your DFA does not recognize $(a|b)^*abb$. For example it does not recognize $abb$.