Question

Give a Deterministic Finite State Automata that accepts Roman numerals.

Answer 1

The DFA for strictly ordered Roman numerals is defined below.
Transitions not indicated go to a rejecting state.  All states, except the start state, are final (accepting) states.

    delta(s,C) = C    delta(s,L) = L          delta(s,X) = X
    delta(s,V) = V    delta(s,I) = I
    delva(L,X) = X    delta(L,V) = V          delta(L,I) = I
    delta(X,X) = XX   delta(X,V) = V          delta(X,I) = I
    delta(XX,X) = XXX delta(XX,V) = V         delta(XX,I) = I
    delta(XXX,X) = XXXX delta(XXX,V) = V      delta(XXX,I) = I
    delta(V, I) = I
    delta(I, I) = II  delta(II, I) = III      delta(III, I) = IIII