... (bdc)*)(dbccdbcc)* Theorem 4.3 The family of regular languages is closed under homomorphism: If L is regular, then so is h(L) Proof Let L(r) = L for some regular expression r Prove: h(L(r)) = L(h(r)) ... representation Standard representation of a regular language is one of the followings: – – – Finite automaton Regular expression Regular grammar Questions about RL Given a regular language L on Σ and any ... and L2 are regular, then so are L1∩L2, L1∪L2 , L1L2 , L1, L1* (The family of regular languages is closed under intersection, union, concatenation, complement, and star-closure.) Proof • L1 = L(r1)...