I am just beginning to learn computation theory. I wrote up a non-deterministic finite automata that accepts strings that contain the substring "abba":
I tried to convert it to a DFA by putting together sets of states in the NFA to be states of the DFA:
However, I just realized that my DFA doesn't accept strings such as "abbaa" that do not end in "abba." That means that my methodology was wrong. Why? I thought it would make sense to combine states of the NFA to make states of the DFA.