# Tagged Questions

Automata Theory, including abstract machines, grammars, parsing, grammatical inference, transducers, and finite-state techniques

68 views

### Finite automata as dynamical systems

In abstract (deterministic finite) automata theory the set of states of an automaton is an arbitrary set Q, and the transistion function is a specific set δ ⊆ Q × Σ × Q (with alphabet Σ, i.e. another ...
65 views

### Does a mathematical construct exists which explains all theories?

If I am not wrong quantum mechanics is about measurements of different physical properties and probabilities of getting different outcomes. We have a mathematical construct to explain it, that is how ...
106 views

### Describe and count the set of sequences containing $20$ or $02$

Let $X = \{ 0,1,2 \}$ be a ternary alphabet and denote by $X^*$ the set of finite sequences (i.e. strings) with three symbols. For $w \in X^*$ with $n$ the length of $w$ and $w = w_1 w_2 \cdots w_n$ ...
55 views

### DFA/NDFA problems confirmation

Im studying for a test on my own and have been working through some previous test questions. Can anyone help me confirm that the answers I've gotten for the problems below are correct or not. If there ...
38 views

### How to design a finite state automaton that recognises the languages like $1^n 0^n$

The question goes like this: Design a finite state automaton that accepts binary strings with at least two $0$s and at most two $1$s. I can easily design an NFA which accepts at least two $0$s OR at ...
48 views

### Is the language $\{yxzx^Ry^R \mid x,y,z \text{ belongs to } \{0,1\}^+ \}$ regular?

This is a question from Iran's national grad school entrance exam. In the answers key, the answer was that the following language is regular but I doubt it is true, I proved using pumping lemma that ...
64 views

### Number of finite-state machines with $n$ states, output alphabet size $a$, and binary input

How many FSMs are there where the machine has $n$ states, reads a binary symbol at each time-step, and may or may not output a symbol from an alphabet of size $a$ after each transition?
22 views

### is language accepted by finte state automaton

Hi I need to prove these languages are accepted or not by the following finite state automata. for 1 does this mean that we need an even number of a's or that a is literally 2,4,6,8....etc also ...
40 views

### Why is this language not regular?

I am studying Automata using the Coursera course created by Jeff Ullman. On slide 36 of this presentation: http://spark-public.s3.amazonaws.com/automata/slides/3_fa2.pdf it says that the language is ...
41 views

### How to simulate a 3-stack automaton with a 2-stack automaton?

Since a 2-stack automaton is Turing-equivalent, it is possible to simulate a 3-stack automaton with just a 2-stack automaton. But how so? How it is normally done?
287 views

### Number of states in a finite automaton

How many states are required by a deterministic finite automaton to store $m$ words each of length $n$? I came across $2^{mn}$ as the solution but there was no explanation.
43 views

### Is the Champernowne constant an automatic number?

The Champernowne constant in base $b \geq 2$ is obtained by concatenating the $b$-ary expansion of every integer. For example, in base $10$ this is $$0.123456789101112131415\dotsc$$ Question: Is the ...
22 views

### Why Petri Net tokens are not added?

Reading this article it says: A firing of an enabled transition removes one token from each input place and adds one token to each output place. Now if I have the following net, with all ...