Write the conversation response. 
 - Finite automata and regular language.
 - Given two deterministic finite automata "A" and "B", it is decidable whether they accept the same language..
 - Are there any other interesting aspects about this article?.
 - 
As a consequence, using the above closure properties, the following problems are also decidable for arbitrarily given deterministic finite automata "A" and "B", with accepted languages "L" and "L", respectively: For regular expressions, the universality problem is NP-complete already for a singleton alphabet.