Questions about mathematical devices that read an input stream symbol by symbol and use a state transition map to produce an output stream, maybe using secondary storage.

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Does a NFA accept context free languages? [on hold]

A NFA accepts regular languages (Type-3). So because of the chomsky hierarchy every regular language is also context-free. So a NFA accepts context free languages. Am I wrong? Moreover a NFA accepts ...
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0answers
41 views

Solvable & Unsolvable Problem Detection [duplicate]

be aware that this problem dosnt have solution. I ran into A multiple choice question on previous midterm on Computation Theory course. this question is which of the following problem is not ...
4
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0answers
61 views

Counting the number of words accepted by an acyclic NFA

Let $M$ be an acyclic NFA. Since $M$ is acyclic, $L(M)$ is finite. Can we compute $|L(M)|$ in polynomial time? If not, can we approximate it? Note that the number of words is not the same as the ...
2
votes
2answers
56 views

Language to Construct Finite State Transducer

I am attempting to write a Finite State Transducer module in OCaml, because I think it's a good exercise, which is because I have been teaching myself Natural Language Processing. You typically ...
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2answers
34 views

How deciding if 2 deterministic finite automatas decide the same language? [duplicate]

Is there any polynomial procedure to decide if 2 deterministic finite automatas decide the same language?
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1answer
66 views

Suffix automaton algorithm to find occurrences of substrings

Here is an attached link to a problem, the Substring query problem that I am trying to solve. It requires the use of suffix automaton,but I could not understand what is a suffix automaton. Can ...
0
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1answer
67 views

A DFA recognizing my name

How can I know if my DFA is implemented correctly? For example, I need to build a DFA, and then minimize it which will recognize my name. Language which describe my name is: L = {pustai, marius} I ...
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3answers
118 views

Problem understanding DFA & NFA equivalence in Theory of Computation

Before asking this question,I had gone through Equivalence of NFA and DFA - proof by construction but my question is a bit different from that. I was reading Michael Sipser's ...
0
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1answer
37 views

Proof that finite automata is closed under intersection

I'm looking at a proof that says that: If $M_1=(Q_1, \Sigma , q_1, A_1, \delta)$ and $M_2=(Q_2, \Sigma , q_2, A_2, \delta)$ are two finite automata(FA) then $M=M_1 \cup M_2$ is also an FA. We define ...
3
votes
3answers
59 views

generate possible inputs valid for automata

I find lots of solution where you have an Automata and a input string , you can validate whether input string is accepted by automata or not. Can we do the reverse ? I am looking for solution which ...
1
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0answers
52 views

(Symbolic) Equivalence of deterministic infinite word transducers with restriction

Given a deterministic infinite word transducer (also called deterministic generalized sequential machine) with the following restriction: There is exactly one initial state All states are final The ...
1
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2answers
92 views

Theory of computation introductory curriculum

I want to study theory of computation on my own, so I am looking for books. What set of books would you recommend for the equivalent of a one-semester course that introduces theory of computation? ...
3
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2answers
93 views

Correspondence between automata and formal grammars?

From Wikipedia Since there is a one-to-one correspondence between linear-bounded automata and such grammars, no more tape than that occupied by the original string is necessary for the string ...
0
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4answers
130 views

How is a nondeterminisitic automaton running on an input?

A nondeterministic automaton, after reading an input symbol at some state, may jump into any of a (finite?) number of states. Does the automaton uniformly randomly choose one out of the several ...
0
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2answers
38 views

Can a language be the one recognized by more than one automatons?

The language recognized by an automaton is defined as the set of strings that are accepted by the automaton. I wonder if it is possible that the languages recognized by two automatons are the same? ...
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1answer
90 views

What does “finite state transduction” mean?

Wikipedia says, the regular languages are closed under arbitrary finite state transductions, like quotient K / L with a regular language. I wonder what kinds of operations "finite state ...
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1answer
30 views

writing a Context free grammar for a language [closed]

Hi I have two question about this language: L = {a^i b^j c^k | i = 2*j OR j=2*k } 1)Finding a CFG 2)If in condition part we put AND instead of OR , is this language remains CONTEXT FREE or not ?? ...
1
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1answer
71 views

Turing Decidable [closed]

M = (Q, Σ, Γ, δ, q1, qaccept, qreject), where Q ={q1, q2, qaccept, qreject}, Σ = {0, 1}, Γ = {0, 1, U}, and transition function δ is as follows: ...
0
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1answer
42 views

Convert regular expression to Automaton

I'm trying to construct a finite-state automaton from the following regular expression: $$ (a|ba)(a|ba)^*(b|ab)^* $$ I know that from $$ (a|ba) $$ the automaton should look something like this: ...
0
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2answers
42 views

Recognizing a language given a Automata

I'm trying to figure out which language can be recognized in this automaton According to wikipedia here "The language L ⊆ Σ* recognized by an automaton is the set of all the words that are accepted ...
6
votes
1answer
210 views

Is the reversal of a minimal DFA also minimal?

The question is pretty much in the title. Is there ever a time where some language $L$ can be accepted by a minimal DFA with $n$ states, but $L^R$, the reversal of $L$, can be accepted by a DFA with ...
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votes
1answer
58 views

Automata Theory Questions: Rule Trees, Context-Free Grammar, Proving Ambiguity [closed]

I'm currently taking a class in Automata Theory and it's kicking my butt. I have an assignment that my teacher gave me that consists of three questions. I have no idea where to start. My teacher and I ...
4
votes
1answer
58 views

NFAs with more than one initial state

I'm trying to give a meaningful definition for NFAs with more than one initial state. I know from the formal definition in Wikipedia that it is possible to have more than one initial state, it ...
0
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2answers
40 views

Automata with no transition for some character

Given an automaton and an alphabet $\{a, b\} $, and the language accepted by the automaton is $ab^*$. Such an automata can be found here: My question is: this automaton cannot process the word ...
5
votes
1answer
106 views

Where/when did Stephen Kleene first define the Kleene closure/star?

I'm working on a paper and would like to review the origins of Kleene's closure. I am unable to find any article of Kleene's that has the original definition of the Kleene closure. Is there a paper ...
1
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1answer
57 views

Turing machine with repeated strings

How would I go about making a Turing machine to accept the following language L? $$L = \{ www \mid w = \{0,1\}^* \text{ and } w > 0\}$$ I was thinking counting the number of symbols in the input ...
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3answers
136 views

Are there any steps or rules to draw a DFA?

In my first lecture of "Theory of Automata", after giving some concepts of Alphabet, Language, transition function etc. and a couple of simple automata of an electric circuit with one and two ...
1
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1answer
38 views

Cellular Automata Using Small Boards

I'm working on making patterns for a digital lava lamp (essentially, making interesting patterns using a 4x10 grid), and I've been looking into cellular automata. I tried implementing some variations ...
1
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2answers
136 views

Help me resolve my doubts about infinities, exemplified by an example of non DFA acceptable language

I have always had a hard time making sense of infinities. Example: the language $L = \{ \epsilon , 01, 0011, 000111, 00001111, ... \}$ is not DFA acceptable because a machine capable of ...
0
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0answers
70 views

Constructing nondeterministic pushdown automata

I having trouble constructing NPDAs for these two languages: $L_1 = \{a^nb^m \mid 2n \le m \le 3n\}$ $L_2 = \{a^nb^mc^k \mid n = m \: or \: m \ne k\}$ Would these be the proper states for the first ...
4
votes
1answer
483 views

how to draw a complement of a Turing Machine?

I am now pretty confident on how I would turn something into a Turing Machine. Now my question is how do you convert TM into a complement of a Turing Machine. From what I can remember in Finite ...
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1answer
47 views

How to read edge labels like “01, 1” on a state diagram?

Is this state machine a moore machine or a mealy machine? I am confused because the states have outputs and the transitions have output based on the input. I tried making a state table but I think ...
1
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2answers
94 views

The language of TMs accepting some word starting with 101

I have a homework question about the properties (decidability, Turing-recognizability, etc.) of the language $$ L = \{ \langle M \rangle | \text{$M$ is a TM and $M$ accepts some string $w$ which has ...
5
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0answers
55 views

Reduction from clique to bag automata

I am trying to figure out a reduction to prove $W[1]$-hardness for this, but I am having significant trouble. Here is the problem: Bag Automaton: A non deterministic finite state automaton ...
4
votes
2answers
60 views

What is Finite Automata Bowl?

I was trying to find info about this Finite Automata type FAB (Finite Automata Bowl) and wasn't able to find a lot. It is basically the rules that apply to PDA apply to FAB except you drop the ...
3
votes
3answers
245 views

Do all states in a DFA must be connected?

Could I construct (for some wired reason) a DFA that has a state that is not connected to anything, and it would still be legal? I'm studying for a test, and I found a question that asks if an ...
9
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1answer
91 views

Computing the intersection of two NPDA where it is possible

Apropois to Raphael's suggestion on Intersection of two NPDAs: Let $A_1$ and $A_2$ NPDA for context-free languages $L_1$ and $L_2$, respectively. Assuming that we know that $L = L_1 \cap L_2$ is ...
5
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2answers
58 views

Intersection of two NPDAs

Is there a way to take the interection of two NPDAs? I can't seem to find anything that can make that happen, but it seems like the type of thing that is should be relatively trival.
2
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1answer
81 views

Are all DFAs also NFAs?

Are all Deterministic Finite Automatons also Non Deterministic Finite Automatons?
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2answers
78 views

How many states when converting CFG to PDA

When converting a CFG to a PDA I know that you get three main states, Qstart, Qloop and Qaccept. But Qloops will need a various amount of states, and my question is how many? Is there a way to find ...
5
votes
2answers
286 views

Why is the halting problem decidable for LBA?

I have read in Wikipedia and some other texts that The halting problem is [...] decidable for linear bounded automata (LBAs) [and] deterministic machines with finite memory. But earlier it is ...
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1answer
32 views

Why it is said that LBA is a non deterministic Turing Machine

I have read that linear bounded automaton is a Non deterministic Turing machine. Why is it so?
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3answers
91 views

What is the distribution of Garden of Eden patterns in cellular automata with increasing pattern size?

In a given cellular automaton, such as Conway's Game of Life, is there anything known about how many Garden of Eden patterns there are by pattern size? Say, pattern size is n x n, what's the ...
12
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8answers
780 views

Why is non-determinism useful concept?

An automaton is an abstract model of a digital computer. Digital computers are completely deterministic; their state at any time is uniquely predictable from the input and the initial state. When we ...
2
votes
1answer
51 views

Why Deterministic PDA accepts $\epsilon$ input but DFA not

I was going through a deterministic PDA that accepts $wcw^R$ (described in Ullman's textbook), in which the last transition is given as $(q_1,\epsilon, Z_0)\to(q_2,Z_0)$, where $q_2$ is the final ...
2
votes
1answer
75 views

What is the difference between RAM and TM

In case of algorithm analysis we assume a generic one processor Random Access Machine(RAM). As I know RAM is machine which is no more efficient than the Turing machine.All algorithms can be ...
2
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1answer
276 views

How turing machine can be used as enumerator

Currently I am studying Turing machines and I understand that a Turing machine can produce all the strings of the language accepted by that particular Turing machine. We call such a Turing machine an ...
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1answer
24 views

In reference to the Chomsky hierarchy (and automatas), Which is the linear feedback shift register Languages/automaton?

The Chomsky hierarchy is a guideline on language expressive power. The linear feedback shift register is a very interesting "element" to structure a language and there is a large theoretical ...
2
votes
1answer
48 views

Are statecharts with parallel states NFA, DFA, or none of the above?

I'm looking for formal statements and proofs that I can make when using SCXML statecharts. As such, I'm trying to categorize it properly. SCXML supports hierarchical states. I believe that any ...
2
votes
3answers
99 views

Language Recognition Devices and Language Generators

I have few CS textbooks with me which discuss languages, well actually 2 plus old course notes supplied a few years ago. I have been searching the web too any only seem to come up with vague responses ...