# Questions tagged [polynomial-time]

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### What are the consequences of $BPP \neq P$?

I have seen a lot of people assume, $BPP = P$ . But to me, this seems false intuitively.(Though math is not without unintuitive results) And, to my admittedly limited understanding of the topic, the ...
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### Complexity of 1-or-3-in-3-SAT (odd-3-SAT)

Consider a 3-CNF formula $\Phi$, i.e., a conjunction of clauses of 3 literals. I call odd-SAT (or 1-or-3-in-3-SAT) the problem of checking whether there is an assignment of the variables such that ...
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### Polynomial vs. Exponential Time Complexity [closed]

Does $2^{log_2{n}}$ grow faster than a polynomial? I know that $2^{log_2{n}}$ can be simplified as $n$ but can it be considered as an exponential?
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### Running time analysis of problems with a variable in problem definition

I am a research scholar in the field of algorithms and complexity theory. The problem that I am currently working is the $[1,j]$-domination problem. Given a graph $G = (V, E)$, $n = |V|$, the problem ...
1 vote
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### Is Maximum Independent Set polynomial-time solvable in $(p,1)$-colorable graphs for general $p$?

It is well-known that Maximum Independent Set (MIS) in bipartite graphs is polynomial-time solvable. What happens if we generalize the input graphs by replacing the vertices in one partite with ...
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### 6-regular graph without small 3-regular subgraph

My name is Balchandar Reddy. I am a research scholar and am currently working on graph algorithms. I am looking to find a 6-regular graph that does not have small 3-regular subgraphs. For example, I ...
114 views

### Computing real numbers with Turing Machines

Consider the following decision problem: Given a two integers $n$ and $k$, decide whether $k=\lfloor n\pi\rfloor$ Question: Is this problem known to be in $P$? Although this may look like a stupid ...
• 475
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### Finding a "typical" path

Consider an undirected graph with two distinguished nodes $u\neq v$. How hard is it to find an $u-v$ path, such that its length is as close to the average $u-v$ path length as possible? Formally, for ...
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### Computation with cellular automata in practice

It is well known that certain cellular automata (CA) are computationally universal, such as Conway's game of life in 2 dimensions or the rule 110 in 1 dimension. As far as I know, they can emulate ...
• 141
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### Is there a natural problem in P but no polynomial time algorithm is known?

Most of the time, a problem is shown to be in P by the construction of a polynomial time algorithm. I wonder if there is a natural problem that was proved in P but no explicit algorithm was known? I'm ...
213 views

### list of 3-CNF formula that can be solved in polynomial time

Suppose i want to program a 3-SAT solver. I want my solver to first check whether a formula is in the list of 3-CNF that currently known can be solved in polynomial time before resorting to brute ...
• 101
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### Can one find any solution to this matrix problem in polynomial time?

I am given an M * N (M > 1, N > 1) matrix with all the numbers blackened but their row and column sums are visible. For example, I am given this 3 * 3 matrix. And one of the possible matrix ...
• 111
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### Solving 3-SAT in O(n^6)?

There's an algorithm (published on GitHub) which is claimed to solve any 3-SAT formulation in polynomial time with a complexity of max O(n^6). I would usually brush claims like this away, but having ...
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• 513
1 vote
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### 3-SAT runtime if an optimal order to eliminate possible solutions is known

As a mental exercise I have been playing around with the 3-SAT problem, but I am having difficulty proving or disproving the usefulness of a current idea that I am playing around with. My current ...
1 vote
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### Young Diagrams and distinguishing between two distributions

Introduction: The reference for everything is this paper. The Robinson–Schensted–Knuth (RSK) algorithm is a well-known combinatorial algorithm with diverse applications throughout mathematics, ...
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1 vote
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### Is polynomial-time the same in all classical computational models?

There are many models of computability, all giving the same notion of 'computable function'. To pick a few examples: Turing machines (with variants: one-ended, two-ended, multiple tapes...) RAM ...
213 views

### Simultaneous evidence for $L\neq NL$ and $P\neq NP$

We believe $L\neq NL$ and $P\neq NP$. Is there any evidence which simultaneously imply $L\neq NL$ and $P\neq NP$?
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• 1,969
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### NP-hardness for one-dimensional facility location problem with entrance fee for each customer [closed]

We have $n$ customers, $(x_1, \dots, x_n)$, sorted on the read line. For convenience, we also use $x_i$ to denote its coordinate on the line. We need to locate $m$ facilities on the real line. We note ...
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1 vote
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### Complexity of a satisfiability problem

I would like the know the complexity of a specific satisfiability problem. I have a feeling it could be solved in polynomial time, but I am not sure about it. The problem is described below. Given $n$ ...
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### Are there enumerations of machines for all languages in 𝑃 such that there exists a simulator that can efficiently run all the machines enumerated?

From Kozen INDEXINGS OF SUBRECURSIVE CLASSES: "the class of polynomial time computable functions is often indexed by Turing machines with polynomial time counters.... The collection of all (...
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### Is there an algorithm for 3x3 sudokus without backtracking? [closed]

From what I can see on Wikipedia and the Internet at large, all sudoku solving algorithms (including human ones) employ some kind of EXPTIME backtracking search for some sudokus. Are there any SAT ...
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### Sequential vs Distributed algo question

If a certain graph problem in the $\textbf{sequential}$ setting is proven to have "no" better constant-factor approximation algorithm than say a 2-approx. algorithm in polynomial time, then does this ...
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1 vote
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### "Relatives" of the shortest path problem

Consider a connected undirected graph with non-negative edge weights, and two distinguished vertices $s,t$. Below are some path problems that are all of the following form: find an $s-t$ path, such ...
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### When can convex optimization be considered to be exactly solvable?

If one is trying to find the global minima of a convex function using gradient descent then one will get a run-time which is a function of $\epsilon >0$ where $\epsilon$ measures the accuracy of ...
• 1,443
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### How to prove a general convex set is nonempty or empty in polynomial time?

The general convex set should be represented by a set of (generalized) inequalities $f_{i}(x)\leq 0$ with $f_{i}(x)$ being convex in $x$. I know ellipsoid method and interior method, but I do ...
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### Complexity of comparing extended integer power towers

Inspired by this stackexchange question, is it an open problem to compare two power towers of positive integers if we additionally allow numbers lower in the tower to themselves be represented by ...
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### Subset sum problem with at most one solution for any target

This question was originally asked on CS.se. A little bit of initial discussion can be found in the comments there. We first consider the search version of the subset sum problem: Given a set $S$ of ...
156 views

### Generalizations of linear programming

Linear problems can be solved in polynomial time. So can semidefinite programs and, presumably, many other useful classes of optimization programs. Is there a survey/lecture notes describing ...
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### P and Descriptive Complexity

In the Complexity Zoo, it says [1] that, in descriptive complexity, $P$ can be defined by three different kind of formulae, $FO(LFP)$ which is also $FO(n^{O(1)})$, and also as $SO(HORN)$. However, ...
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### Is Circuit Minimization $P$-hard under logspace reductions?

By Circuit Minimization, I am referring to the following decision problem. Circuit Minimization Input: A bit string $x$ and a number $k$. Question: Does there exist a Boolean Circuit $C$...
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### Why is the "general notion of a reduction [...] inherent to the notion of self-reducibility"?

While reading "Computational Complexity: A Conceptual Perspective" by Oded Goldreich, I have come across the following passage, which I simply cannot get my head around: Note that the general ...
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### Complexity of counting integer roots of multivariate polynomials in a polyhedron?

Deciding integer roots of multivariate polyomials is undecidable. However what is known about counting integer roots of multivariate polynomials in $\mathbb Z[x_1,\dots,x_m]$ with both $m$ and total ...
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I am interested in the problem of deciding if a cut-set of a given size $k$ (i.e. the number of edges crossing the partitions is $k$) exists in a given bipartite graph (both the graph and $k$ are part ...
Consider the following problems: Orthogonal Vectors Problem Input: A set $S$ of $n$ Boolean vectors each of length $d$. Question: Do there exist distinct vectors $v_1$ and $v_2 \in S$ ...