We now add an additional degree of non-determinism and allow transitions that can be taken independent of the input-ε-transitions.

Here whenever the automaton is in state 1 it may make a transition to state 3 without consuming any input. Similarly, if it is in state 0 it may make such a transition to state 2. The advantage of such transitions is that they allow one to build NFAs in pieces, with each piece handling some portion of the language, and then splice the pieces together to form an automaton handling the entire language. To accommodate these transitions we need to modify the type of the transition relation to allow edges labeled ε.