Our built-in tools help you complete, sign, share, and store your documents in one place.
Make edits, fill in missing information, and update formatting in US Legal Forms—just like you would in MS Word.
Download a copy, print it, send it by email, or mail it via USPS—whatever works best for your next step.
Sign and collect signatures with our SignNow integration. Send to multiple recipients, set reminders, and more. Go Premium to unlock E-Sign.
If this form requires notarization, complete it online through a secure video call—no need to meet a notary in person or wait for an appointment.
We protect your documents and personal data by following strict security and privacy standards.

Make edits, fill in missing information, and update formatting in US Legal Forms—just like you would in MS Word.

Download a copy, print it, send it by email, or mail it via USPS—whatever works best for your next step.

Sign and collect signatures with our SignNow integration. Send to multiple recipients, set reminders, and more. Go Premium to unlock E-Sign.

If this form requires notarization, complete it online through a secure video call—no need to meet a notary in person or wait for an appointment.

We protect your documents and personal data by following strict security and privacy standards.
What is closure? Recall that a set S is closed under an operation X if the output of X is in S whenever the inputs were in S. So, for example, saying that the regular languages are "closed under union" means that if P and R are regular languages, then so is the union of P and R.
Regular Languages are closed under intersection, i.e., if L1 and L2 are regular then L1 ∩ L2 is also regular. L1 and L2 are regular • L1 ∪ L2 is regular • Hence, L1 ∩ L2 = L1 ∪ L2 is regular.
A set is closed under an operation if applying that operation to any members of the set always yields a member of the set. For example, the positive integers are closed un- der addition and multiplication, but not divi- sion. Fact. The set of regular languages is closed under each Kleene operation.
Closure under Union For any regular languages L and M, then L ∪ M is regular. Proof: Since L and M are regular, they have regular expressions, say: Let L = L(E) and M = L(F). Then L ∪ M = L(E + F) by the definition of the + operator.
Regular languages are closed under concatenation - this is demonstrable by having the accepting state(s) of one language with an epsilon transition to the start state of the next language. If we consider the language L = {a^n | n >=0}, this language is regular (it is simply a).
Closure Properties of Regular Languages Given a set, a closure property of the set is an operation that when applied to members of the set always returns as its answer a member of that set. For example, the set of integers is closed under addition.
Regular languages are closed under union, concatenation, star, and complementation.
Regular Languages are closed under intersection, i.e., if L1 and L2 are regular then L1 ∩ L2 is also regular. L1 and L2 are regular • L1 ∪ L2 is regular • Hence, L1 ∩ L2 = L1 ∪ L2 is regular.
Intersection. Theorem If L1 and L2 are regular languages, then the new language L = L1 ∩ L2 is regular. Proof By De Morgan's law, L = L1 ∩ L2 = L1 ∪ L2. By the previous two theorems this language is regular.
Reversal. Statement: Under reversal, the set of regular languages is closed. Proof: Let M be a deterministic finite automaton that accepts L; we will create M' from M so that M and M' states are the same. Make the final state of M the accepting state of M' and the final state of M the beginning state of M'.