Emptiness problem, Theory of Computation

Assignment Help:

The Emptiness Problem is the problem of deciding if a given regular language is empty (= ∅).

Theorem 4 (Emptiness) The Emptiness Problem for Regular Languages is decidable.

Proof: We'll sketch three different algorithms for deciding the Emptiness Problem, given some DFA A = (Q,Σ, T, q0, F).

(Emptiness 1) A string w is in L(A) iff it labels a path through the transition graph of A from q0 to an accepting state. Thus, the language will be non-empty iff there is some such path. So the question of Emptiness reduces to the question of connectivity: the language recognized by A is empty iff there is no accepting state in the connected component of its transition graph that is rooted at q0. The problem of determining connected components of directed graphs is algorithmically solvable,by Depth-First Search, for instance (and solvable in time linear in the number of nodes). So, given A, we just do a depth-?rst search of the transition graph rooted at the start state keeping track of whether we encounter any accepting state. We return "True" iff we ?nd none.


Related Discussions:- Emptiness problem

Turing machine, prove following function is turing computable? f(m)={m-2,if...

prove following function is turing computable? f(m)={m-2,if m>2, {1,if

Find a regular expression, Find a regular expression for the regular langua...

Find a regular expression for the regular language L={w | w is decimal notation for an integer that is a multiple of 4}

Local myhill graphs, Myhill graphs also generalize to the SLk case. The k-f...

Myhill graphs also generalize to the SLk case. The k-factors, however, cannot simply denote edges. Rather the string σ 1 σ 2 ....... σ k-1 σ k asserts, in essence, that if we hav

Construct a regular expression, Given any NFA A, we will construct a regula...

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

Gephi, construct a social network from the real-world data, perform some si...

construct a social network from the real-world data, perform some simple network analyses using Gephi, and interpret the results.

Graph Connectivity, Let G be a graph with n > 2 vertices with (n2 - 3n + 4)...

Let G be a graph with n > 2 vertices with (n2 - 3n + 4)/2 edges. Prove that G is connected.

Chomsky normal form, s->0A0|1B1|BB A->C B->S|A C->S|null find useless symbo...

s->0A0|1B1|BB A->C B->S|A C->S|null find useless symbol?

Automaton theory, let G=(V,T,S,P) where V={a,b,A,B,S}, T={a,b},S the start ...

let G=(V,T,S,P) where V={a,b,A,B,S}, T={a,b},S the start symbol and P={S->Aba, A->BB, B->ab,AB->b} 1.show the derivation sentence for the string ababba 2. find a sentential form

REGULAR GRAMMAR, Find the Regular Grammar for the following Regular Express...

Find the Regular Grammar for the following Regular Expression: a(a+b)*(ab*+ba*)b.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd