nfa

I found a same question on this website, and the answer was a PDF describing how to convert an NFA to a regex . But this is not working because this method has some conditions: There are transitions going from the initial state to all other states, and there are no transitions into the initial state. There is a single accept state that has only transitions coming into it (and no outgoing transitions). The accept state is distinct from the initial state. Except for the initial and accepting states, all other states are connected to all other states via a transition. In particular, each state

I'm currently working on a scanner generator. The generator already works fine. But when using character classes the algorithm gets very slow. The scanner generator produces a scanner for UTF8 encoded files. The full range of characters (0x000000 to 0x10ffff) should be supported. If I use large character sets, like the any operator '.' or the unicode property {L}, the nfa (and also the dfa) contains a lot of states ( > 10000 ). So the convertation for nfa to dfa and create the minimal dfa takes a long time (even if the output minimal dfa contains only a few states). Here's my current

In DFA we can do the intersection of two automata by doing the cross product of the states of the two automata and accepting those states that are accepting in both the initial automata. Union is performed similarly. How ever although i can do union in NFA easily using epsilon transition how do i do their intersection? You can use the cross-product construction on NFAs just as you would DFAs. The only changes are how you'd handle ε-transitions. Specifically, for each state (q i , r j ) in the cross-product automaton, you add an ε-transition from that state to each pair of states (q k , r j )