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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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Show that, for any languages L1 and L2, we have (1). L1L1^* = L1^*L1L1^*

I am taking Automata Theory and Formal Languages and am confused on how to work out #3 from my HW. The link to HW is provided in the following: https://www.eecs.wsu.edu/~zdang/c317/Assignments/homework1.pdf For 3.1 I know that L1L1^* is essentially…
Alex
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Efficiently check if path is valid in graph using NetworkX?

I would like to find an efficient way to check if a given "Walk" through a graph is valid. Such a function should accept a Graph (nodes, edges) and a string of node names, and should output True if nodes can be visited in the given sequence…
SirSteel
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Constructing Finite State Machine

What are the major issues essential to consider when constructing a finite state machine representing a given language? I know that finite state machines take strings as inputs, and that as each element of the string is read, the machine state…
RomM
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L = { a^n b^n c^m d^m : n >= 1, m >= 1 } U { a^n b^m c^m d^n : n >= 1, m >= 1 } isRegular?

there is a lot of examples for pumpinglemma proof, but I did not figure out this, can anyone help ? L= { a^n b^n c^m d^m : n >= 1, m >= 1 } U { a^n b^m c^m d^n : n >= 1, m >= 1 }
John Nick
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How to remove ambiguity in following grammar?

S -> Sa | SbSa | ε I found a similar question but i don't understand : http://automatasteps.blogspot.co.id/2007/08/unambiguous-grammar.html How do i change this to the unambiguous one? My string is bbaaa
Ricky
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Context free grammar where # of one terminal equals difference of other two

The language is defined as follows: L = {a^m b^n c^k | k = |m-n| } So a's followed by b's followed by c's, where the number of c's is the absolute value of the a's minus b's. I can't figure out how to capture this behavior in a CFG. Any advice?
AnthonyG
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Turing Machine calculator

Can someone give me a code of example for Turing Machine Calculator which can accept these inputs 30+25x3-2/5= and the output is 104.6 this calculator cant accept these input 3+52-2 43+1=12 0+12+1= 2+0+x2= 1x02= +2+3= x19x1= 12x2x=
nadinna
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context free grammar for the following language

{a^i b^j c^k | i != j j=k} I am able to write the productions where #a = #b or #a != #b. But here, there are two condiitions. I tried writing the following production but here, #c is not equal to #b. S-> YC Y-> aYb | bB | aA A->aA|e B->bB|e …
I_Love_Islam
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A non-negative integer base 3

I am actually having problem in understanding what does this actually mean : "a non-negative integer base 3" In In theory of computations, when we program something to check the membership of a WORD in a LANGUAGE. We do certain checks. But in this…
user8181313
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What does the pound sign represent in a language?

L = { w#w#w | w ϵ {0,1}* } What are some string outputs for this language? The pound sign is throwing me off. Is it the same as www? For example w = 01 so 010101 is in the language of L?
Anymee
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if there is a production that contains a nonterminal nullable, then is that production nullable?

I was wondering, if I got a production that contains a nonterminal nullable, then is that production nullable? A → aB | ε B → bA | e in this example, is B nullable because A is nullable?
user6003740
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Set of conditions for Finite Automata transitions

What kind of Finite Automata supports set of conditions for transaction from state A to state B? For example, if (a && b && c) then A -> B. To make it even harder, let's say that we receive one condition at a time. of course it could be done with…
Федор Дао
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Can a finite automata have more than one input states?

I was knowing that Finite Automata can have only one input states but several output states. Recently, I've come across an example of removing ^-moves that has many input states. Please help!
Vibhor Agarwal
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Context Free Grammar to PDA

Can this grammar be converted to a PDA? `S-> aS | EPSILON ` I think no because I cannot define how much “a” to push-pop.
user9039337
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Hierarchical State Machine in IEC 61131-3

I would like implement a HSM in 61131-3. Doing some reading I understand that HSM's are a sort of subset of pushdown automata? Most of the examples from other languages are using pointers and references, which I would like to avoid. Is it feasible…
krakers
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