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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".

692 questions
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Turing machine states design

I want to design a Turing machine that accepts at most 3 0s. Now, I have designed one, which goes to accept state overtime it sees 1, 2 and 3 0s and rejects any further 0s. I wanted to know if it is okay for TM to go to accepting state from 3…
user9179677
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Trying to draw a Non- Deterministic Finite Automata

I'm completely new to finite automata and kind of struggling to understand the topic. I'm able to draw simple ones but I have a practice question that asks to: Design a Non- Deterministic Finite Automata that accepts ∑={0,1}. The Non-Deterministic…
John Diggle
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I dont understand why i get an ArrayIndexOutOfBoundsException 2 error

I am trying to make a program that does cellular automata in 1D. For that, i need to read three variables from a single line. one of the variables, "L", determines the array length of "currentGeneration". However I get the ArrayIndexOut... error. I…
Amaan V
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Implementing a queue by Turing machine

How can I implement queue by Turing machine?
Eyal
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Prove that regular languages and context free languages are recursive

I am a bit confused with the difference between regular and context free languages. A recursive language is a language, for which there exits a TM which always halts. I am facing problem in proving the above statement.
Mukesh Gautam
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How to determine which language is simpler

The following language is the complement of a simpler language. Construct a DFA for the simpler language and then use it to give the state diagram of a DFA for the given language where Σ = {a,b}. L={ w : w does not contain the substring baba}. I…
nmorsi
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need help finding the context free grammar of these languages

I need help finding the grammar of these languages. I feel like I am getting nowhere with these solution 1) {a^h b^k a^m b^n | h + k = m + n} 2) {a^i b^j a^k | (i = j and k ≥ 0) or (i ≥ 0 and j > k)} any help would be appreciated
marc k
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Give context-free grammars that generate the following language

Give context-free grammars that generate the following language. In all parts the alphabet ∑ is {x,s}. {w| w starts and ends with the different symbols}
Muhammad Shahid Khan Afridi
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Lexical analyser : how to identify the end of a token

I need a function that identifies the end of token so that i can save in it an array and send it to my automata for identification(Operator,Keyword,Identifiers) the automata is working great when i enter only 1 token , but when there is `lots of…
Sierra
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number of dfa's that can be designed

Can we calculate the total number (i.e maximum no.) of dfa's that can be designed when the following constraints are put: |Q|=2{No. of states is 2},|Ɛ|=2{No. of alphabets} and |F|=1{No. of Final States} ?
Sharat Ainapur
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Constructing Language generated by the grammar

We have to find L(G), where grammar G is given as- S->AB|CD, A->aA|a ,B->bB|bC, C->cD|d, D->aD|AD I have attempted the question but it is recursing very deep and I am unable to terminate the string.[I know that A will generate a^n after n steps…
Rachit Belwariar
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How to draw a DFA for given language?

Give a finite state diagram for a DFA that accepts any word in the language L = {w | w ∈ {a, b}∗ and w alternates a’s and b’s and has an even number of b’s}. My attempt: I am having problem on how to deal with the even part of b.
max
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What will be the e-closure(r) in following NFA

Sorry guys I cannot provide the pic here...I was unable to upload the pic...so.. I will give the transition table of the problem. (S/I)....a...b.....c.......e(elipson) p>.......{p}.....{q}...{r} ..¤(phi) q>.......{q} ....{r} ..¤.... {p}…
Akshay kumar
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meaning of B={x:{a,b}*|na(x)=nb(x)} in automata?

meaning of B={x:{a,b}*|na(x)=nb(x)} in automata while creating a production for context free grammar?
aishwarya sharma
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About Regular Expression

Set={a,b} and L7:"All words that begin with an a and end with a b" is given L7 can be defined by a(a+b)*b What is the meaning of "+" ? And, How to solve this problem ?
Hakan Hakyemez
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