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Questions tagged [automata]

In theoretical computer science, automata theory is the study of abstract 'mathematical' machines or systems and the computational problems that can be solved using these machines. These abstract machines are called automata. ("Automata", Wikipedia)

From Wikipedia,

Automata, or automata theory, is the study of mathematical objects called abstract machines or automata and the computational problems that can be solved using them. Automata comes from the Greek word αὐτόματα meaning "self-acting".

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Is this grammar context free or not?

G: S ---> aSb S ---> λ As tought me the first production rule is context-free (because the left side is less than right side) but for second production rule, it isn't (because the left side length equals the right side). Well, what can we…
NoWeDoR
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DFA that accepts strings over {b} of length 2i+5k for any non-negative values of i and k

DFA that accepts strings over {b} of length 2i+5k for any non-negative values of i and k? What will be the solution to this?
akkk
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npda for the language number a's less than or equal to 3 times the number of b's

I am trying to construct an npda for L = {w ∈ {a,b}*| na(w) <= 3*nb(w)}. This means that for every b there can be at most 3 a's. First of all, this is what I have done so far. From the start state, we push a single "a" on to the stack. (at the…
John
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Strings that {b U a}* Accepts (Kleene Star)

So I understand that something like b* accepts epsilon, b, bb, bbb, etc. However, when I take the union of these two characters, what types of strings are accepted by the language? Is babababa accepted?
jonnyd42
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Pumping Lemma Assistance

I recently had an assignment where I was asked to use pumping lemma to show that a language was not regular, and unfortunately got the wrong answer. The language to prove is non-regular is as follows: L = {ai bj ck: i = j or j = k} The definition…
Ben Rogers
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Regular language closure under insertion

Suppose I have a regular language L under alphabet Σ. How do I show that the language L' is still a regular language when I insert a symbol in the middle? For example, L includes a string w which consists of two substrings u and v (w = uv) I want to…
Darren B
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Can a Finite Automata exist without any final state?

It doesn't make sense to construct a language acceptor which does not able to accept any language. I specifically talking about FA which accept languages not transducer or translator which translate languages.
lifeisshubh
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Definition of a language in Automata Theory

I'm currently taking a class in Automata Theory, and while still at Finite Automata, I do find it both interesting and challenging. We are using 'Introduction to Automata Theory...' by Hopcroft and it talks about a DFA in the notation: A = (Q,Σ, δ,…
Lobs001
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how can i get weighted finite automaton?

1.how can i get this automaton(non blocking and weighted)? 2.I want to see some simple examples.
박순서
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Is there any CFG available (with pos tags -part of speech tags) to validate the grammar of sentences in english?

It may not be 100 % accurate but still is there any written and tested CFG. is it available with nltk data?
pradeepsng30
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Regular expression 0+10*+01*0 convert to NFA

My main issue is figuring out the 10* and 01* states. This is what I have so far: image
tadashi
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What formalism doesn't belong and which are more powerful/equal

I have this list of formalisms and i need to order them according to their expressive power, also one of them doesn't really belong. Context-free Grammar(CFG) Deterministic Finite Automata(DFA) Deterministic Pushdown Automata(DPDA) LR(0)…
Conviley
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{a^nb^n} union {a }is deterministic or not

I am confused according to me it should not be deterministic as there will be states for (a,zo/azo) going to q1 and (a,z0/eplison) going to final state. Is this true or not
simranjit singh
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show that emptiness and finiteness are unsolvable for linear bounded automata

Show that emptiness and finiteness are unsolvable for linear bounded automata, I didn't understand, Can anyone help me out?
Ranjan Yadav
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Binary division and DFA

wanted to know whether binary division concept come from DFA i.e. from finite automata? According to me the dfa would have lead to the binary division bcz we do binary divisons in computers only and we know that dfa have forms the base of computers…
skyconfusion
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