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Questions tagged [nondeterminism]

Questions about automata, formal grammars or other computation-models that specifically relate to the use of nondeterminism. Not to be confused with randomness or ambiguity!

See here for why and in which way and are not the same!

Fitting category tags are and/or . Other related tags include , , , , , , and probably more.

Note that in the context of grammars, nondeterminism should not be confused with , either!

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What is the difference between quantum TM and nondetermistic TM?

I was going through the discussion on the question How to define quantum Turing machines? and I feel that quantum TM and nondetermistic TM are one and the same. The answers to the other question do not touch on that. Are these two models one and the…
bongubj
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Differences and relationships between randomized and nondeterministic algorithms?

What differences and relationships are between randomized algorithms and nondeterministic algorithms? From Wikipedia A randomized algorithm is an algorithm which employs a degree of randomness as part of its logic. The algorithm typically uses …
Tim
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Why is non-determinism a useful concept?

An automaton is an abstract model of a digital computer. Digital computers are completely deterministic; their state at any time is uniquely predictable from the input and the initial state. When we are trying to model real systems, why include…
Tanmoy Banerjee
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What is meant by "solvable by non deterministic algorithm in polynomial time"

In many textbooks NP problems are defined as: Set of all decision problems solvable by non deterministic algorithms in polynomial time I couldn't understand the part "solvable by non deterministic algorithms". Could anyone please explain that?
user5507
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What are the conditions for a NFA for its equivalent DFA to be maximal in size?

We know that DFAs are equivalent to NFAs in expressiveness power; there is also a known algorithm for converting NFAs to DFAs (unfortunately I do now know the inventor of that algorithm), which in worst case gives us $2^S$ states, if our NFA had $S$…
Daniil
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How to prove that DFAs from NFAs can have exponential number of states?

All non-deterministic finite automata can be turned into equivalent deterministic finite automata. However, a deterministic finite automata only allows a single arrow per symbol pointing from a state. Therefore, its states should be members of the…
John Hoffman
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Defining the halting problem for non-deterministic automata

The primary definition of Turing machine (TM), at least in my own reference textbook (Hopcroft+Ullman 1979) is deterministic. Hence my own understanding of the halting problem is primarily for deterministic TM, though I am aware that it may be…
babou
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Why NFA is called Non-deterministic?

I have this [kind of funny] question in mind. Why is the non-deterministic finite automaton called non-deterministic while we define the transitions for inputs. Well, even though there are multiple and epsilon transitions, they are defined which…
Madhusoodan P
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Classfication of randomized algorithms

From Wikipedia about randomized algorithms One has to distinguish between algorithms that use the random input to reduce the expected running time or memory usage, but always terminate with a correct result in a bounded amount of time, and …
Tim
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Why is NFA minimization a hard problem when DFA minimization is not?

I know that we can minimize DFAs by finding and merging equivalent states, but why can't we do the same with NFAs? I'm not looking for a proof or anything like that--unless a proof is simpler to understand. I just want to understand intuitively…
Duncan
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Can we say DFA is more efficient than NFA?

I just started reading about theory of computation. If we compare which is more powerful (in accepting strings), both are same. But what about efficiency ? DFA will be fast compared to NFA, since it has only one outgoing edge & there will be no…
avi
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Why nondeterminism?

Theory of computation often involves nondeterministic models of computation. Some examples include nondeterministic finite automata (NFAs), nondeterministic pushdown automata (PDAs), and nondeterministic Turing machines. Real computers, however, are…
Yuval Filmus
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Computational power of deterministic versus nondeterministic min-heap automata

This is a follow-up question of this one. In a previous question about exotic state machines, Alex ten Brink and Raphael addressed the computational capabilities of a peculiar kind of state machine: min-heap automata. They were able to show that the…
Patrick87
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How does an NFA use epsilon transitions?

In the picture below, I'm trying to figure out what exactly this NFA is accepting. What's confusing me is the $\epsilon$ jump at $q_0$. If a $0$ is entered, does the system move to both $q_0$ and $q_1$ (the accept state)? If a $1$ is entered,…
user3472798
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Push Down Automatons "guess" - what does that mean?

I realize non-deterministic pushdown automata can be an improvement over deterministic ones as they can "choose" among several states and there are some context-free languages which cannot be accepted by a deterministic pushdown. Still, I do not…
lisa
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