# Non-isomorphic minimal non-deterministic finite automata

Can somebody provide an example of two equivalent (recognizing the same language) minimal non-deterministic automata (NFA) which are not isomorphic?

## 2 Answers

See the paper (postscript)

Arnold, Dicky, Nivat. A note about minimal non-deterministic automata

• Thank you for sharing! Their paper includes a nice example. :) – Michael Wehar Jun 11 '15 at 5:10

Along a different line: the set $L_6$ of strings of the form $a^n$, where $n$ is not a multiple of 6 has two very different minimal NFAs.

One of them is basically the minimal DFA, the other guesses whether it is not a multiple of 2 or not a multiple of 3.