Simulate Deterministic Finite Automata validating passwords and email addresses in parallel
Each constraint is a regular language recognized by a DFA β a 5-tuple M = (Q, Ξ£, Ξ΄, qβ, F).
Final validation = intersection of all DFA languages:
Email is decomposed into 3 DFAs: structure ([email protected]), single-@ check, and consecutive-dot check. Each runs independently and acceptance is intersected for the final result.
Product construction on all constraints causes state explosion. Running DFAs independently and intersecting acceptance is clean and efficient.