Questions tagged [automata-theory]

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Certain type of regular languages

Dear All, there is one type of regular languages, over $\{a,b\}$, which appear naturally in what I am studying, so if anybody could recognise them, or say any sort of their characterisation, that ...
Victor's user avatar
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Intersection of cone types

Let $G$ be a finitely generated hyperbolic group with the word metric; fix a symmetric generating set $S$ and let $\mathcal{G}$ be the Cayley graph of $G$ w.r.t. $S$. Define the cone of an element $x\...
EM90's user avatar
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Estimating the growth rate of nondeterministic finite automata

Given a nondeterministic finite automaton $\mathcal{A}$ (or a regular expression, or a regular grammar), can we efficiently compute the number $|L_k(\mathcal{A})|$ of accepted words of length $k$? No,...
David's user avatar
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Question about $\omega$-regular languages

As most of you already know, in model checking most linear-time properties are either safety properties or liveness properties. A linear time property is usually described with an $\omega$-regular ...
Y.H.'s user avatar
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2 answers
139 views

A question on regular sets

In the end of the Abstract of the paper Minsky and Papert - Unrecognizable Sets of Numbers, the authors write "…for every infinite regular set $A$ there is a nonregular set $A'$ for which $$ \...
Beta's user avatar
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Proof that the $\omega$-language consisting of all words containing every finite word as a factor is not rational/regular

Let $\eta$ be an $\omega$-word over $X = \{0,1\}$ and let $F_k(\eta)$ denote the factors of $\eta$ of length $k$. Define the following $\omega$-languages $$ L_k := \{ \xi : F_k(\xi) = X^k \} = \{ \xi ...
StefanH's user avatar
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1 answer
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Varieties of rational languages and (pseudo-)varieties of finite monoids, question regarding closure property

Let $\mathcal Rat(A)$ denote the class of rational (or regular) languages over the alphabet $A$, a subset $\mathcal V(A) \subseteq \mathcal Rat(A)$ is called a variety of (rational) languages iff ...
StefanH's user avatar
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1 answer
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Busy beaver sequence for a simple tag-like system

This question arose in the context of tag-like systems, specifically Bitwise Cyclic Tag (BCT). Consider the following discrete dynamical system: Let $\mathbb{B} = \{\mathtt{0}, \mathtt{1}\}$. Let our ...
user76284's user avatar
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2 votes
1 answer
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For synchronizing eulerian finite state machines every proper subset of states has some larger state set leads to this subset

Suppose we have a deterministic complete finite automaton which is synchronized, meaning we have a reset word, i.e. a word which resets the automaton to a definite state, regardless from which state ...
StefanH's user avatar
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Understanding the paper: "Guarded Fixed Point Logic"

This question is specifically about the paper "Guarded Fixed Point Logic" by Gradel and Walukiewicz. Among other things they prove the decidability of the satisfiability problem for Fixpoint Loosely ...
Alberto's user avatar
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How does "inhibitor arc" fit into fundamental equation of Hybrid Petri Nets?

In "ON HYBRID PETRI NETS" by DAVID AND ALLA published in 2001 on page 26 is given an example of how fundamental equation solves a HPN for given start and end time values. A system looks like And ...
DuckQueen's user avatar
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1 answer
141 views

Representability of sets of infinite sequences sharing common prefixes and factors (i.e. infixes)

Here we are concerned with the space $X^{\omega}$ of infinite sequences. Denote by $F_n(\xi)$ the set of factors (consecutive finite subsequences) of length $n$ and consider the set $$ K_n(\xi) = \xi[...
StefanH's user avatar
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1 answer
283 views

Universality of blind graph rewriting

Let us consider $S(M) = \{(f_0, f_1) | f_0, f_1: M \rightarrow M\}$, where $M$ is a finite set. Each element of $S(M)$ is equivalent to a finite directed graph with the set of nodes $M$, which has ...
Anton Salikhmetov's user avatar
2 votes
1 answer
204 views

QBF of exponential length?

We consider a slightly extended version of a nondeterministic finite automaton, call it a "propositional nondeterministic finite automaton". It is defined as follows. Consider a fixed propositional ...
user109711's user avatar
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A particular generalization of free partially commutative monoids

A trace monoid, or free partially commutative monoid, is one with the presentation $\langle \Sigma \mid a_1b_1 = b_1a_1, \dots, a_nb_n = b_na_n\rangle$. The theory of trace monoids has been well ...
rotas's user avatar
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Name for the theory of words with equal length, prefix, successors

I've worked with this theory for a while, but I've never been quite sure what to call it: $$(\Sigma^*, =_{el}, \preceq, (S_a)_{a \in \Sigma})$$ Where $\Sigma^*$ is the set of finite words on finite ...
TomKern's user avatar
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0 answers
102 views

Why can a least fixed point operator only be expanded finitely many times?

If we expand modal logic with least and greatest fix point operators $\mu$ and $\nu$, respectively, we obtain the logic $L_\mu$. An alternating automaton on infinite trees has a state space that is ...
Max's user avatar
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0 answers
65 views

If a timed automaton always terminates, does there exist a trace with a maximum length?

I have a theoretical question regarding timed automata and I would like to know if someone has already given an answer to it, since that would be useful for my research. So my question is the ...
Panos Vasilikos's user avatar
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Relation between indexed languages (OI-macro or context-free tree) and scattered context languages

I'm not sure about the relation between indexed languages (generated by indexed grammars--Aho) and scattered context languages (generated by scattered context grammars--J Hopcroft). I think that ...
Nate's user avatar
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1 answer
414 views

Given a PDA M such that L(M) is in DCFL construct a DPDA N such that L(N) = L(M)

Is it possible to construct an algorithm which takes as input a pushdown automaton $M$ along with the information that the language accepted by this automaton $L(M)$ is a deterministic context-free ...
Sam Jones's user avatar
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1 answer
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Non-regular languages fulfilling the Pumping Lemma

Some non-regular languages don't yield to the Pumping Lemma ($L_1=a^nb^mc^m$ should work). But now consider the set of non-regular languages L only over the alphabet {a}. (Like $L_2=a^{n^2}$ or ...
Hauke Reddmann's user avatar
1 vote
1 answer
248 views

The automorphism groups of smallest grammars of a language string are isomorphic

Let $s \in \Sigma^*$ be a formal language string. Consider the automorphism group of $s$, defined to be the set of all permutations of positions of $s$ that leave $s$ fixed. For instance $G(abab) = \...
Daniel Donnelly's user avatar
1 vote
2 answers
2k views

Translate a buchi automaton to LTL

How can I translate a Büchi automaton A to LTL(linear temporal logic) if $L(A)$ is definable in the LTL? MY idea is : Büchi automaton $A$ ===> QPTL ===> LTL I know that given any Buchi ...
LimaoLogic's user avatar
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1 answer
2k views

example :concatenation of 2 undecidable language gives a decidable language [closed]

give example of 2 languages A and B such that A and B are undecidable but there concatenation A.B is decidable.
shreya's user avatar
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1 answer
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If a language $L$ is accepted by a non-deterministic automation, then $L$ is regular [closed]

The following lemma is from the book Discrete groups by Ohshika. If a language $L$ is accepted by a non-deterministic automaton, then $L$ is regular, i.e., there exists a finite state automaton $M$ ...
one potato two potato's user avatar
1 vote
1 answer
395 views

Let G and H be finite index subgroups of a free group. Does GH=HG?

Let $\Sigma$ be a finite set. Let $F_\Sigma$ be the free group over $\Sigma$. Let $G$ and $H$ be finite index subgroups of $F_\Sigma$. Consider the sets $GH$ and $HG$. Is it always true that $GH=HG$? ...
Jonathan Mosheiff's user avatar
1 vote
1 answer
151 views

Shortest word accepted by a PDA

Given a pushdown automaton (PDA), we seek a shortest word accepted by it. A standard approach is to map the problem in the corresponding context-free grammar. Can we analyze and solve this problem ...
lchen's user avatar
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1 answer
179 views

decidability of regularity of a language depending on representation

It is well known that many decision problems for regular languages are decidable. However, the proofs seem to rely on a witness of the regularity of said language, be it an automaton, a grammar, a ...
Sebastian Mueller's user avatar
1 vote
1 answer
155 views

Errors in Waksman's Solution to Cellular Automaton Firing Squad Problem?

Recently, a student and I have been working through Waksman's paper ``An Optimum Solution to the Firing Squad Synchronization Problem.'' The paper claims that for any value of $n$, the proposed ...
Andrew Penland's user avatar
1 vote
1 answer
108 views

Minimal DFA of L* [closed]

I'm learning how to minimize DFAs. Are the number of states in the minimal DFA of L, is equal to the number of states in the minimal DFA of L*? I'm trying for hours to think of examples but couldn't ...
Barak michaeli's user avatar
1 vote
1 answer
344 views

Modal logic in combination with automata theory

I'm planning to write a paper about the possibility of describing modal logic and the multiple world aspect of it with techniques of automata theory. To not duplicate my work does anyone have more ...
blub's user avatar
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1 vote
1 answer
158 views

Optimum control of a probabilistic automaton

Suppose we have a probabilistic automaton and we assign a weight to each state. An "interaction strategy" would be a fixed map from states to inputs. Any interaction strategy could be used to ...
Joseph Soulbringer's user avatar
1 vote
1 answer
242 views

Dumb question about Minimization in IATLC

I have probably a pretty dumb question about the classical Minimization algorithm for a DFA, as described in the Hopcroft book "Introduction to Automata Theory, Languages and Computation", pg. 155-164....
minimindless's user avatar
1 vote
0 answers
63 views

Does Frobenius number increase if bound on input increases?

The Frobenius number F is the largest number not expressible as a non-negative linear combination of some set of positive integers $\{a_i\}$, where, $a_i$ has gcd 1. Denote $maxF(n)$ as the maximum of ...
Drinkwater_84's user avatar
1 vote
0 answers
55 views

Effect on finite transformation semigroup under a particular modification of the generators

The following question arises in connection with problems in automata theory related to the road problem. Let $f_1, f_2: [N] \to [N]$ be maps such that the transformation semigroup $S = \langle f_1, ...
Sophie M's user avatar
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1 vote
0 answers
73 views

What a generating function for a language tells us about the language [closed]

What a generating function for a language tells us about the language .I need its answer in base of automata?
Salman Khalid's user avatar
1 vote
0 answers
261 views

Characterization of non-Zeno functions $f:\mathbb{R}\rightarrow \{0,1\}$

[Edit: I tried to integrate Nate's comments (see below).] In the context of automata over continuous time, consider Boolean-valued functions $f:\mathbb{R}\rightarrow \{0,1\}$. There are uncountably ...
Hans-Peter Stricker's user avatar
1 vote
0 answers
251 views

What does homomorphism between languages mean to the correspoding Turing Machines?

According to the article: every c.e.language over $\Sigma^*$can be formed by homomorphism from a Dyck language over $\Sigma^{'}$ intersection with a minimal linear language over $\Sigma^{'}$ to the ...
XL _At_Here_There's user avatar
1 vote
0 answers
295 views

Life. Intermediate stages

My question is pure mathematics when restricted to the cellular automata theory. John von Neumann got the grasp of and defined life. Many years later biologists supported von Neumann's definition of ...
Włodzimierz Holsztyński's user avatar
1 vote
0 answers
228 views

LTL - Büchi-automaton Translation [closed]

I need some help in Generalized Büchi automaton .. I do understand the translation of a LTL-formula ϕ into Generalized Büchi automaton A= (Q, Δ, I, F), with F= {F1,...,Fn} My problem is F .. I know ...
sansun's user avatar
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1 vote
0 answers
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Question about link between non-terminals of grammars and variables of Diophantine equations

If we change the right arrow in the rewriting rules of grammar into equators , changes all terminals into x and keep the non-terminals unchanged,we get system of equations.In some cases,those ...
XL _At_Here_There's user avatar
1 vote
0 answers
228 views

What is this structure called?

(I'm not entirely sure what to tag this; feel free to retag.) While thinking about automata (specifics below), I ran into the following phenomenon: A cofunction system is a pair of sets $X, A$, ...
Noah Schweber's user avatar
1 vote
0 answers
108 views

Schönhage's SMM with only one instruction

It is possible to implement $\lambda$-calculus in Schönhage's storage modification machine using an infinite set of nodes and one single program consisted exclusively of (about hundred) instructions ...
Anton Salikhmetov's user avatar
0 votes
2 answers
236 views

Verification of Turing-equivalent automata

Correct me if I slept in my computer science studium: If an automaton is Turing-equivalent, the Halting problem shows that there are programs we can not verify (since we can't even predict their ...
Hauke Reddmann's user avatar
0 votes
1 answer
285 views

A Nomenclature Issue : Imprimitive Semigroup?

The following question was asked by me on the forum sci.math.research, “An imprimitive group is a transitive permutation group with a non-trivial equivalence relation compatible with the action of ...
Nobody's user avatar
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0 answers
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A cellular automaton with an image that is not closed

Let $G$ be a non-locally finite periodic group and let $V$ be an infinite-dimensional vector space over a field $\mathbb{F}$. Does there exist a nontrivial topology on $V^G$ and a linear cellular ...
mahdi meisami's user avatar
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0 answers
58 views

First-order logics expressively equivalent to the computable languages

There is a really nice theorem that the subsets of $(\Sigma^*, =_{el}, \preceq, (S_a)_{a \in \Sigma})$ definable in first-order logic are exactly the regular sets. Where: $\Sigma^*$ is the set of ...
TomKern's user avatar
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0 votes
0 answers
28 views

Probabilistic timed automata transition

I am kind of new to timed automata and I have a question related to their correctness and synchronisation. Assume that I have three states, A, B and C. I have also two clocks, $x$ and $y$ that are ...
Ecterion's user avatar
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0 answers
152 views

Proof of conjecture that permutation-free automata restrict the possible states visitable from a stringset sharing prefixes and infixes

An automaton $\mathcal A = (X, Q, \delta, q_0)$ is called permutation-free iff no word $w \in X^*$ induces a nontrivial permutation of a subset of the states of $\mathcal A$. More formally for any $R \...
StefanH's user avatar
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-1 votes
1 answer
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prove (a+b)*=a*(ba*)* [closed]

formal language and automata theory regular expessions (a+b)* =a*(ba*)* please answer I want the proof thank you
abhinand's user avatar