Lecture 8 - Finite Automata and Non-Regular Languages

Question 1

___________ many and exactly _ of all _________ over any ________

Answer 1

Uncountably; C; languages;
alphabet Σ != ∅

Question 2

_ infinitely countably many regular languages

Answer 2

ℵ0

Question 3

___________ many and exactly _ _________ that are not _______

Answer 3

Uncountably many; C languages; regular

Question 4

A language L ⊆ Σ*
is regular iff.

Answer 4

There is a regular
expression r ∈ R that represents L, i.e. such that L = L(r)

Question 5

For any regular language L, its reverse language L^R is _______

Answer 5

regular

Question 6

What is a Pumping Lemma? What is it used for?

Answer 6

one of a general class of Theorems
called pumping theorems; used as a tool to carry proofs that some languages are not regular

Question 7

What does the Pumping Lemma assert?

Answer 7

the existence of certain points in certain strings where a substring can be repeatedly inserted (pumping) without affecting the
acceptability of the string

Question 8

Why is the book pumping lemma special?

Answer 8

It is a stronger version of PL 2. It applies to any regular language, not to an infinite regular language as PL 1 & PL 2.