Stack Overflow
Stack Overflow

Questions tagged [automata-theory]

Automata theory studies classes of algorithms which can be defined using abstract machines (automata). Classes of automata differ in terms of restrictions to which they are subjected; for the most common classes, the primary difference concerns memory and how transitions between states may access it. More powerful classes can define more powerful algorithms; according to the Church-Turing thesis, no real machine is more powerful than Turing Machines.

166 questions
13
votes
4 answers

Can a DFA have epsilon/lambda transitions?

Can´t find anything affirmative about it. And a NFA with any epsilon transition is a epsilon-NFA ? Thanks.
liwing
  • 211
  • 2
  • 3
  • 8
7
votes
2 answers

Implementing A Nondeterminisic Finite Automaton(NFA)

I'm trying to a develop a simulation that executes a non deterministic finite automaton in Java. The first command line argument is a text file that defines the machine. The second argument is an input string. If it accepts the string, it prints to…
donth77
  • 605
  • 1
  • 12
  • 23
6
votes
1 answer

LR(1) - Items, Look Ahead

I am having difficulties understanding the principle of lookahead in LR(1) - items. How do I compute the lookahead sets? Say for an example that I have the following grammar: S -> AB A -> aAb | b B -> d Then the first state will look like this: S…
mrjasmin
  • 1,230
  • 6
  • 21
  • 37
5
votes
1 answer

Pushing/popping stack in reverse order in a Pushdown Automaton

So I'm studying for a test I have coming up on pushdown automata and context-free languages and I'm stuck on this one construction. I have every part of this automaton completely working perfectly except for one part which I will explain below. The…
JayB
  • 397
  • 6
  • 21
4
votes
1 answer

What type of languages are accepted by a PDA in which stack size is limited?

What type(s) of languages are accepted by a PDA in which stack size is limited to, say 20 items? In my view it should still be CFL, because there is a temporary memory to store.
Prashant Bhardwaj
  • 1,203
  • 2
  • 18
  • 26
4
votes
2 answers

Notation for concat in set theory

I'm working on homework for a automata theory class. So far its just proofs involving regular expression nothing too crazy. Anyway, my question is this what is the proper set notation for concatenation? For example I know R + S would be the same as…
Pinsickle
  • 623
  • 2
  • 10
  • 20
4
votes
2 answers

How many languages does a DFA recognize?

According to Sipser's "Introduction to the Theory of Computation": If A is the set of all strings that machine M accepts, we say that A is the language of machine M and write L(M) = A. We say that M recognizes A ... A machine may accept several…
Paolo Mazza
  • 73
  • 1
  • 6
4
votes
3 answers

Regular Expression to DFA

Can someone tell me if the attached DFA is correct ? I am suppose to give DFA for the language that has alphabet Σ ={a, b} I need DFA for this ----> A={ε, b, ab}
Jon Abraham
  • 851
  • 3
  • 14
  • 27
4
votes
2 answers

How can one simulate nondeterministic finite transducers?

A nondeterministic automaton can be simulated easily on an input string by just keeping track of the states the automaton is in, and how far in the input string it has gotten. But how can a nondeterministic transducer (a transducer, of course, can…
oskarkv
  • 2,329
  • 2
  • 21
  • 29
3
votes
2 answers

PDA for {a^n b^m | n<=m<=2n}

Can someone help me design PDA for {a^n b^m | n<=m<=2n}. Can you please design one with explanation.
RJ Naskar
  • 31
  • 1
  • 2
3
votes
2 answers

Automata programming language

Do you know any programming language that implements abstract machines like Turing machines and Finite State Automatons? That is, process the following input: A 5-tuple (The notorious ⟨Q,Σ,δ,q0,F⟩ from formal languages 101), a 7-tuple for Turing…
Adam Matan
  • 128,757
  • 147
  • 397
  • 562
3
votes
1 answer

Is OpenGL a "state machine"?

OpenGL is usually described as a "state machine" because, as far as I know, it consists of global variables which can be set through its API and they change/define its behavior. For example it is possible to set current color or transformation…
Ali Shakiba
  • 20,549
  • 18
  • 61
  • 88
3
votes
1 answer

DFA for this language

Σ={ a, b, c, d } L={ x ∈ Σ* | x does not start or end with "bab" } Examples that should be accepted: ababa ababc bbabb bbaba ab ba aaaa ɛ Examples that should be rejected: bab baba babc cbab abab I tried several times, and got this so…
user1697973
3
votes
2 answers

Grammar to Regular Expression

Which is the procedure steps to find the regular expression that accept the same language of a given Grammar? S --> b | AA A --> aA | Abb | ϵ
Whando
  • 31
  • 1
  • 1
  • 3
3
votes
5 answers

Finiteness of Regular Language

We all know that (a + b)* is a regular language for containing only symbols a and b. But (a + b)* is a string of infinite length and it is regular as we can build a finite automata, so it should be finite. Can anyone please explain this?
Madhudeep Petwal
  • 83
  • 2
  • 7
1
2 3
…
11 12