Universality problem, Theory of Computation

The Universality Problem is the dual of the emptiness problem: is L(A) = Σ∗?

It can be solved by minor variations of any one of the algorithms for Emptiness or (with a little less work) it can simply be reduced to Emptiness.

Theorem (Universality) The Universality Problem for Regular Languages is decidable.

Proof: L(A) = Σ*⇔ L(A) = ∅. As regular languages are effectively closed under complement we can simply build the DFA for the complement of L(A) and ask if it recognizes the empty language.

Posted Date: 3/21/2013 1:55:24 AM | Location : United States

Related Discussions:- Universality problem, Assignment Help, Ask Question on Universality problem, Get Answer, Expert's Help, Universality problem Discussions

Write discussion on Universality problem
Your posts are moderated
Related Questions
1. Does above all''s properties can be used to prove a language regular? 2..which of the properties can be used to prove a language regular and which of these not? 3..Identify one

We developed the idea of FSA by generalizing LTk transition graphs. Not surprisingly, then, every LTk transition graph is also the transition graph of a FSA (in fact a DFA)-the one

Can you say that B is decidable? If you somehow know that A is decidable, what can you say about B?

design a turing machine that accepts the language which consists of even number of zero''s and even number of one''s?

i have some questions in automata, can you please help me in solving in these questions?

The Recognition Problem for a class of languages is the question of whether a given string is a member of a given language. An instance consists of a string and a (?nite) speci?cat

Given any NFA A, we will construct a regular expression denoting L(A) by means of an expression graph, a generalization of NFA transition graphs in which the edges are labeled with

If the first three words are the boys down,what are the last three words??

Paths leading to regions B, C and E are paths which have not yet seen aa. Those leading to region B and E end in a, with those leading to E having seen ba and those leading to B no

The universe of strings is a very useful medium for the representation of information as long as there exists a function that provides the interpretation for the information carrie