Paper 4, Section I, 4H4 \mathrm{H}

Automata and Formal Languages
Part II, 2017

(a) Describe the process for converting a deterministic finite-state automaton DD into a regular expression RR defining the same language, L(D)=L(R)\mathcal{L}(D)=\mathcal{L}(R). [You need only outline the steps, without proof, but you should clearly define all terminology you introduce.]

(b) Consider the language LL over the alphabet {0,1}\{0,1\} defined via

L:={w01nw{0,1},nK}{1}.L:=\left\{w 01^{n} \mid w \in\{0,1\}^{*}, n \in \mathbb{K}\right\} \cup\{1\}^{*} .

Show that LL satisfies the pumping lemma for regular languages but is not a regular language itself.