Questions tagged [automata-theory]
Automata Theory, including abstract machines, grammars, parsing, grammatical inference, transducers, and finite-state techniques
-2
votes
0answers
54 views
Closure of rational langages under morphisms
I have to prove that the set of rational or regular languages is closed by morphism on their alphabet.
i.e. that the image of a rational language by a morphism is still rational.
h being a morphism ...
3
votes
1answer
67 views
Agnostic query learning for DFAs
Angluin's membership+equivalence query algorithm allows to efficiently and exactly learn a target $n$-state DFA. But what if the target DFA is huge, or the target concept is not even a regular ...
4
votes
0answers
82 views
Complexity of DFA intersection in this specific case?
In general, the size of the DFA that recognizes the intersection of $n$ languages is exponential in $n$. However, in my case I am computing the intersection of a very restricted subset of possible ...
0
votes
0answers
114 views
Where does a C-like language without heaps belong in the automata hierarchy?
Assume that the language C', unlike C, has well-defined semantics, but has similar features: pointers and manual memory management through malloc and free. Assume that C'' is the same as C' without ...
2
votes
0answers
94 views
Notion of “quotient” or “inverse” for recognizable tree languages?
Related to my previous question but this time I have a better idea of what I'm actually asking.
I'm looking at the following operation on recognizable tree languages (i.e. regular tree grammars, ...
2
votes
0answers
48 views
Regular Tree Languages are closed under quotient?
The Wikipedia page for Regular Tree Grammars notes that if $L_1$ and $L_2$ are regular tree languages, than $L_1 \setminus L_2$ is as well. However, it doesn't define this quotient operation for trees,...
8
votes
1answer
189 views
Turing Machines as Coalgebras
I'm looking to write a survey on the method of representing the dynamics of state-based computation within the framework of coalgebras. So far I've managed to find papers on coalgebra representations ...
8
votes
1answer
136 views
A conjecture related to the Cerny conjecture - counterexample/reference request
The Cerny conjecture is the statement that any synchronizing automaton with $n$ states has a synchronizing word of length at most $(n-1)^2$. The best current upper bound for the length of a ...
3
votes
2answers
142 views
Compactness of domino tilings
I've read in Lemma 2 of the paper 1 that if every square region of the plane admits a tiling, then the whole plain admits a tiling, but the proof is omitted. This sounds like a compactness property, ...
2
votes
1answer
120 views
Name for a special family of languages?
I was wondering whether there is a standard name in the literature for the following family $\mathcal{F}$ of languages over any finite alphabet $\Sigma = \{a_1,\ldots,a_k\}$:
$\mathcal{F}$ consists ...
2
votes
1answer
98 views
Automata as term rewriting systems
It came to my mind that automata (say to start DFA) can be thought as a special kind of rewriting systems. So if one has a word w , one tries to reduce it to the $\epsilon$ word. In other words ...
9
votes
3answers
374 views
Continuous mathematics and formal language theory
Whether there are some results on solving formal languages problems using mathematical analysis, continuous mathematics.
For example, solving the intersection non-emptiness problem for a context-free ...
10
votes
2answers
243 views
Does a given regular language contain an infinite prefix-free subset?
A set of words over a finite alphabet is prefix-free if there are no two distinct words where one is a prefix of the other.
The question is:
What is the complexity of checking whether a regular ...
4
votes
1answer
112 views
Applications of Christol theorem
I'm looking forward to know about applications of Christol theorem mentioned in Jefrrey Shallit's Number theory and formal languages. One of them is purely algebraic: if $f, g \in \mathbb{F}_q[[z]]$ ...
9
votes
0answers
89 views
Are there cascade decompositions of machines that are more general than finite automata?
The idea of decomposing automata and their associated semi-groups into irreducible sub-components is due to Krohn & Rhodes and has been explored relatively thoroughly. Krohn & Rhodes gave an ...
7
votes
2answers
350 views
Are all turing machines paths predictable?
I was recently studying partial solutions to the halting problem and came across the problem which I discuss below. In particular I was studying when it was computable to tell if a turing machine has ...
1
vote
0answers
40 views
Question About Turing Machine Computability [closed]
If p is a Turing machine then L(p) = {x | p(x) = yes}.
Let A = {p | p is a Turing machine and L(p) is a finite set}.
Is A computable? Justify your answer.
So I'm trying to figure out how to solve ...
13
votes
2answers
634 views
Automata learning without counterexamples
In Angluin's automata learning framework, a student aims to learn a regular language $L\subseteq \Sigma^*$ by asking two types of questions to his teacher:
Word queries: given $w\in \Sigma^*$, is $w\...
4
votes
0answers
69 views
Libraries for programming automata and Turing machines
What are the most useful libraries around for coding related to automata and Turing machines?
By useful I mean the number of functions and algorithms supported by it.
9
votes
0answers
123 views
Shortest string in the intersection of regular languages
Inspired by https://codegolf.stackexchange.com/questions/53310/shortest-universal-maze-exit-string
Each of the 138,172 valid mazes can be represented as a DFA with 9 states (including starting and ...
2
votes
1answer
82 views
Can a det. $k$-counter machine ($k \geq 2$) be simulated by a det. $k'$-counter machine using non-$\epsilon$-moves followed by $\epsilon$-moves?
I have a question concerning deterministic $k$-counter machines, for $k \geq 2$. Recall that in this context, the determinism is expressed by the fact that the machine can never face a choice between ...
2
votes
0answers
73 views
Characterization of deterministic pushdown automata
Is there any known characterization for deterministic pushdown automata (DPDA)?
For example, visibly pushdown automata(VPA) is a subclass of DPDA, which is characterized by following syntactic ...
1
vote
0answers
56 views
Rational power series over $\mathbb N \cup \{\infty\}$, rationality of singular part
Let $\Sigma$ be a finite alphabet, and consider the formel power series over $\Sigma$ considered as non-commuting variables with coefficients in the semiring $\mathcal N := \mathbb N \cup \{\infty\}$ ...
3
votes
1answer
131 views
“Combining” two mealy machines [closed]
How could you combine two mealy machines, the first one $M_1$ has as input $\sum_{1}^*$ and as output $\sum_{2}^*$,
the second machine $M_2$ uses the output $\sum_{2}^*$ as the input and outputs $\...
3
votes
3answers
106 views
Example of monoid $M$ such that $\operatorname{RAT}(M) \not\subseteq \operatorname{REC}(M)$
Let $M$ be a monoid, the family of rational sets $\operatorname{RAT}(M)$ is defined as the smallest set containing the finite subsets, and closed under union, concatentaion and the star operation. The ...
9
votes
1answer
132 views
Generalisation of the statement that a monoid recognizes language iff syntactic monoid divides monoid
Let $A$ be a finite alphabet. For a given language $L \subseteq A^{\ast}$ the syntactic monoid $M(L)$ is a well-known notion in formal language theory. Furthermore, a monoid $M$ recognizes a language $...
-4
votes
1answer
49 views
Prove that L* is a regular language [closed]
Suppose that L is any language , not necessarily regular, whose alphabet is {0}; that is the strings of L consist of 0's only. Prove that L* is regular.
5
votes
1answer
105 views
Closure of Recognizable Languages under Kleene Star: Algebraic Proof?
Let $Rec(\Sigma)$ be the class of languages over $\Sigma^*$ recognizable by finite monoids.
To show that $Rec(\Sigma)$ is closed under Kleene star, one would usually refer to the equivalence of ...
2
votes
1answer
230 views
Existence of an algorithm
I need to show that there exists a polynomial time algorithm that inputs a deterministic automata $A$, and decides if $A$ accepts a word w if and only if it also accepts any word obtained by permuting ...
7
votes
1answer
184 views
Finding a minimal DFA whose language has a desired intersection with another
Suppose I have regular languages $B \subseteq A$, with corresponding (known) minimal deterministic finite automata $M_A, M_B$.
I would like to find another regular language $C$ such that $B = A \cap ...
-1
votes
1answer
42 views
Push Down Automata [closed]
Can we put more than one element in stack at a time.
Actually I am asking that this transition function is valid for PDA:
∆(q,a,z)=(q',aaz)
Where:
q and q' are states
a is input symbol
z is starting ...
3
votes
0answers
87 views
Looking for a specific tree automata model
is there any tree automata model over unranked trees (that is with unbounded number of children for each node), such that:
Checking non-emptiness and universality is decidable in elementary time,
...
22
votes
2answers
485 views
Testing whether letters can be scheduled to achieve a word in a regular language
I fix a regular language $L$ on an alphabet $\Sigma$, and I consider the following problem that I call letter scheduling for $L$. Informally, the input gives me $n$ letters and an interval for each ...
4
votes
1answer
249 views
Is it known if $CFL \subseteq NSPACE(o(log^2(n)))$?
$CFL$ is the class of context-free languages.
Question
Is $CFL$ known to be solvable in $o(log^{2}(n))$ non-deterministic space? What about $DCFL$?
-1
votes
1answer
91 views
When designing a DFA, am I allowed to design two separate Machines and perform an Intersection on them? [closed]
I am trying to design a DFA s.t. The set of strings in x ∈ {0, 1}∗
such that the number of zeros is a multiple of 3 and the number of one's is even.
My idea was to create two Machines M1 = (Q1, Σ, δ1,...
13
votes
1answer
696 views
Complexity of the problem of words with fewest distinct letters accepted by a finite automaton
Given a finite (deterministic or nondeterministic, I don't think this has much importance) automaton A and a threshold n, does A accept a word containing at most n distinct letters?
(By k different ...
12
votes
1answer
135 views
Regular language that discriminates between two deterministic CFGs
Suppose you are given two deterministic push down automata which recognize languages $A$ and $B$, and wish to determine whether there is a regular language $R$ such that $A \subseteq R$ and $R \cap B =...
7
votes
1answer
131 views
Random Deterministic Automata
I am familiar with the term of random graphs, such as $G(n,p)$- a distribution over simple undirected graphs with $n$ vertices, where each edge appears in a graph w.p. $p$. That is, each graph $G=(V,E)...
1
vote
1answer
104 views
Set of languages that can represent every c. e. languange
Could we find any set of languages $S$, such that it can represent every c. e. languange as it's union, intersection, complement, production(times of element ), and $S\subset X$, where $X\subseteq c.e....
3
votes
1answer
65 views
Can any c.e. language with infinite words be decomposed into infinite CFLs with infinite words?
Suppose $L$ is a computably enumerable language, can it be decompose into infinite CFLs with infinite words ?
$$L=\bigcup_{L_i\in CFL }^{\infty}L_i$$
Second question: if it is possible that every $L$...
-1
votes
1answer
74 views
Is there an inherently ambiguous language which can not be recognized by Deterministic LBA?
Is there inherently ambiguous language which can not be recognized by Deterministic LBA?
For example, $L=\{wv: w,v=(x|y)^*, w=w^R,v=v^R\}$, is there any deterministc LBA that recognizes $L$ ?
1
vote
0answers
456 views
Equality Constraints over Sets with Tree Automata
Tree Automata can be used to model sets of values of a Herbrand Universe, for example, to model possible values in a functional program.
Systems of subtype constraints over set expressions have ...
5
votes
1answer
183 views
What is the motivation behind defining Deterministic Looping Automata?
I was wondering about what could possibly be the motivation behind defining the deterministic looping automata? What puzzles me is that they accept a word iff they have a run on it!
I believe they ...
2
votes
1answer
214 views
Deformation of finite regular languages [closed]
Let $L \subseteq \{0,1\}^n$ be any finite regular language s.t it has an acyclic DFA.
Let $C$ be some class of acyclic DFAs.
Let $\sigma \in S_n$ be a permutation on $n$ symbols. We can apply $\...
4
votes
1answer
1k views
Is Hartmanis-Stearns conjecture settled by this article?
The paper
"On the computational complexity of algebraic numbers: the Hartmanis--Stearns problem revisited"
by Boris Adamczewski, Julien Cassaigne, Marion Le Gonidec
https://arxiv.org/abs/1601....
9
votes
3answers
262 views
Class of languages recognizable by single-tape 3-state TMs
I have for a while been curious about Turing Machines with exactly one tape and exactly 3 states (namely the start state $q_0$, the accept state $q_{accept}$, and the reject state $q_{reject}$). Note ...
1
vote
0answers
76 views
Relation between MDPs and non-deterministic finite automatons
I'm confused as to the relation (computability-wise) between markov decision processes and NFAs. Are finite state MDPs expressible as regular grammars? If so, are markov decision processes thus ...
1
vote
0answers
99 views
Convenient forms of Turing machines
Let us suppose that I have defined a new convenient form of the Turing machine for processing of some specific sort of commonly used structures.
This form of TM contains some specific features ...
6
votes
1answer
420 views
Pumping Lemma over 2 way Automaton
Pumping Lemma essentially implies that for a NFA $N$ having $N_0$ states over a unary language $L_0$ any string belonging to $L_0$ can be obtained by 'pumping' one of the strings that have a length ...
6
votes
1answer
222 views
Has there been a study of circuits operating on arrays?
Much ink has been spilled studying the theory surrounding computation by combinatorial circuits operating on bits or boolean values - with AND, OR and NOT gates (as those are enough to implement any ...
