Questions tagged [p-vs-np]
The p-vs-np tag has no usage guidance.
169
questions
24
votes
5answers
7k views
P = NP clarification
Let's use Traveling Salesman as the example, unless you think there's a simpler, more understable example.
My understanding of P=NP question is that, given the optimal solution of a difficult problem,...
1
vote
1answer
2k views
A problem in NP but not NP-complete?
Graph isomorphisim is not proven to be NP-complete what would it imply if it were possible to prove that there are some problems which are in NP set of problems but not in NP-complete set.
0
votes
1answer
30 views
how to proof ${ NPC \bigcap CO-NPC \ne \varnothing then NP = P ? }$
how proof ${\ \ NPC \ \ \bigcap \ \ CO-NPC \ne \varnothing }$ then
${NP = P ? }$
0
votes
0answers
37 views
How to know if a problem belongs to NP Class?
What I know (NOT strictly speaking): I know that there is an open question about the equality of P and NP Classes and as long as there is no known algorithm that solves NP problems in P time then we ...
0
votes
1answer
79 views
P Vs NP can never be proven one way or the other!
Okay, so I was reading a bit about P vs NP problems. And I found out that proving P Vs NP is an NP problem.
And since if we prove that any problem in NP is a P that would mean that we have NP=P.
...
0
votes
1answer
47 views
Does computational complexity theory take into account problems with subjectivity in the verification of a solution?
When we discuss P vs NP we are looking at the difference between problems that are easily solved versus easily verified (wrt polynomial vs exponential time).
But in both cases these are black-and-...
4
votes
3answers
2k views
If a problem is in P solved via dynamic programming, is it also in NP?
So I can solve a given problem using dynamic programming in $O(n^2k^2)$ time complexity. This means that the problem is in P. But I am asked if it is in NP.
My answer is, "Since it is also polynomial ...
0
votes
1answer
175 views
How to prove Exact cover problem is NP Complete using Vertex Cover problem?
Using reduction theorem in NP, we want to prove that Exact cover is NPC by reducing it from Vertex Cover Problem. It is easy to derive it from SAT, but we can't find a solution yet to derive it from ...
0
votes
1answer
111 views
Is this statement of P = NP in Agda correct?
Looking for a self-contained statement of P = NP in type theory, I stumbled upon this short Agda formalization (a cleaned up version is reproduced below).
The statement here does seem to express the ...
1
vote
0answers
35 views
Weaker conjectures to prove in order to arrive at P =/= NP
We know we have a long way to go before we come to a proof of P $\neq$ NP. We also know that this road is studded with minor conjectures that will have to be proved/disproved in order to arrive at the ...
2
votes
1answer
48 views
How is $\text{PCP}[O(\log n),O(1)]$ NOT P?
As a prover, we just try to convince the verifier that it's correct, no matter whether it is or not. So we can just analyze every possible route.
For $\text{PCP}[O(\log n),O(1)]$, won't there just be ...
0
votes
0answers
42 views
Confusion about P versus NP [duplicate]
I'm sure that in my following question my reasoning is extremely simplistic and flawed, but I think if someone answered this it would help me understand what the P vs NP conundrum is. So here is my ...
-1
votes
1answer
161 views
Baker, Gill, Solovay - construction of oracle B such that P^B != NP^B
I have some questions about Baker, Gill, Solovay proof of the existence of an oracle such that P^B != NP^B. The proof can be found in Siam Journal of Computing, 4:432-442, 1975 [219].
Why Isn't this ...
1
vote
2answers
183 views
P/NP - Polynomial Reduction vs Certificate
I am learning about the P/NP problem right now, and I don't understand when to use polynomial reduction and when to use a certificate.
How I understand polynomial reduction is that you can use it to ...
2
votes
1answer
68 views
Doubts about Baker-Gill-Solovay
How am I supposed to read the P=?NP relativization proof? I am reading the classical paper Relativization of the P=?NP problem by Baker, Gill and Solovay, in particular the proof that there exist an ...
2
votes
3answers
124 views
Is the P vs NP problem, an NP or co-NP problem?
A few years ago, a youtube channel named hackerdashery, made an extraordinary youtube video explaining P vs NP, in a semi-vulgarized way :
https://www.youtube.com/watch?v=YX40hbAHx3s
At 7 minutes ...
-1
votes
3answers
452 views
One-way Trapdoor Function
Do the functions of the collatz conjecture and their inverses model a Trapdoor Function?
If given a, b, a^-1, b^-1 and your choice of f(x), is it “hard in the average case” to find some secret x?
I ...
5
votes
1answer
181 views
P vs. NP and Godel's Theorems
This post is based loosely on a previous post, but the presentation is somewhat different and hopefully much more succinct.
Basically, I'm wondering if it is plausible for there to be a formal proof ...
1
vote
1answer
174 views
P vs NP question from GeeksforGeeks
From here: https://www.geeksforgeeks.org/algorithms-np-complete-question-2/
Let S be an NP-complete problem and Q and R be two other problems not known to be in NP. Q is polynomial time reducible to ...
2
votes
2answers
250 views
What's the flaw in the P != NP proof in the article “The Computational Complexity of the Traveling Salesman Problem”
I am reading through some proof of inequality of P and NP
but they are not accompanied by the flaws in the reasoning so I'm trying to find them by myself, just to see if I'm getting the logic right. ...
10
votes
2answers
4k views
Contradiction proof for inequality of P and NP?
I'm trying to argue that N is not equal NP using hierarchy theorems. This is my argument, but when I showed it to our teacher and after deduction, he said that this is problematic where I can't find a ...
1
vote
1answer
91 views
A tricky P=NP problem
Define an operator $\pi(\cdot)$: for a language $L$, $\pi (L)$ is the set of all prefixes of strings in $L$ with length at least half of the original string. Prove that if $\mathsf{P}$ is closed under ...
0
votes
0answers
27 views
Reducing SAT to a P problem in polinomial time [duplicate]
Does reducing SAT in polynomial time to a P problem would mean that P = NP?
2
votes
1answer
97 views
What is Ironic complexity? What are some good resources to learn about it?
The term "Ironic complexity" was coined by Scott Aaronson for the stuff Ryan Williams does in the area of complexity theory. Could anyone tell me what kind of problems and approaches does Ryan ...
7
votes
1answer
2k views
If graph isomorphism is in P, is then P = NP?
I think that, since graph isomorphism is not known to be $\textbf{NP}$-complete, we can not reduce all problems in $\textbf{NP}$ to it, and therefore the implication does not hold.
Additionally, in ...
0
votes
1answer
40 views
Effective Procedures and P vs NP Problem
If, suppose, P doesn't equal NP. Implication of this statement is that there is no effective procedure to solve a hard problem; however there exists an acceptable solution S. I have following two ...
1
vote
1answer
266 views
Why any problem can be reduced to SAT is NP-Complete?
I have a book statement says the title, I don't understand it. From my current understanding if a problem A can be reduced to a problem B then it only means B is at least as difficult as A.
3
votes
2answers
116 views
Given that A reduces to B in $O(n^2)$ and B is solvable in $O(n^3)$, solve A
Suppose a problem A reduce to problem B and reduction is done in $O(n^2)$ time.
If problem B is solved in $O(n^3)$ time then what about the time complexity of problem A?
Approach:
A is reduced ...
0
votes
1answer
94 views
Can we detect perfect matchings in P? in NP? in coNP?
This question concerns the classes P and N P . If you are familiar with them, you may skip the definitions and go directly to the question.
Let L be a set. We say that L is in P if there is some ...
2
votes
1answer
77 views
Are there problems that are DSPACE(O(1)) complete?
I know there are problems that are NL-complete, NP-Complete, PSPACE-complete, etc. Are there problems that are DSPACE(O(1))-complete I.e. NSPACE(O(1))-Complete I.e. Reg-Complete?
Thanks!
1
vote
0answers
95 views
What can be a Zero Knowledge Proof of a working SAT Algorithm?
Me and my colleague are exploring new ideas to solve SAT efficiently (i.e. in polynomial time) and it's the case that there is a candidate algorithm.
Unfortunately, neither of us can write scripts ...
0
votes
1answer
69 views
Does indirect diagonalization a relativize technique?
My main question is can with R.kanon , Fortnow ,... technique that shows lower bounds for SAT seperate P and NP ?
Baker-Gill-Solovay showed that $P?=NP$ could not be solved with relativization. Does ...
3
votes
1answer
484 views
Chomsky Hierarchy and P vs NP
I have read multiple questions here that involve this kind of subject but I haven't found any definite answer. In what class do regular languages belong? (P or NP or some regular are P and other NP), ...
0
votes
1answer
71 views
Are there infinite possibilities to the outcome of the P vs. NP question?
The P vs. NP poll provides 3 possibilities: equal, not equal, and independent. This is reasonable, because despite the law of the excluded middle you must supply a proof for your answer, which itself ...
1
vote
1answer
36 views
What's wrong with the following argument that $NP \subset coNP$? [duplicate]
What's wrong with the following argument that $NP \subset coNP$?
let $L \in NP$; then there exists an NTM $N$ that decides $L$ in $f(n)$ time where $f(n) = O(n^k)$ for some natural number $k$.
...
6
votes
2answers
192 views
Does Provable P equal Provable NP?
My question is a very basic one. It seems feasible to believe that $\mathsf{P = NP}$, because there is some "pathological" good algorithm for SAT, yet it is impossible to prove that the algorithm is ...
1
vote
1answer
342 views
P vs NP problem (Student example)
Hello dear stackexchangers,
I have a simple question, and I would like to say that I am not a scientist. When I read the problem statement on this link: http://www.claymath.org/millennium-problems/p-...
4
votes
1answer
221 views
Logical characterization of P versus NP problem (and references for least fixed point logic)
Wikipedia says the following (and more) about the logical characterization of the P versus NP problem here:
Thus, the question "is P a proper subset of NP" can be reformulated as "is existential ...
2
votes
2answers
382 views
P vs NP and can an oracle make P=EXPTIME?
As I understand, diagonalization cannot be used to prove or disprove P vs NP, because for some oracle $A$, $P^A = NP^A$, whereas under another oracle $B$, $P^B \neq NP^B$.
I don't fully understand ...
0
votes
1answer
61 views
Independence Implies P $\ne$ NP
Suppose P vs. NP is independent of ZFC. Then there cannot be an efficient SAT solver, otherwise it would constitute a proof for P = NP. Therefore P $\ne$ NP.
What we see here is that independence ...
8
votes
2answers
772 views
Why doesn't Godel's Second Incompleteness Theorem rule out a formalizable proof of P!=NP?
I'm sure there must be something wrong with the following reasoning because otherwise a lot of P vs. NP research would be curtailed but I cannot determine my error:
For any fixed integer $k>0$ ...
3
votes
2answers
167 views
How are boolean circuits used for solving P vs NP?
In the paper https://web.stanford.edu/~gavish/documents/sipser-pvsnp.pdf , it is mentioned under the Status section that boolean circuits have been used to try and solve P vs NP. Can anyone explain to ...
2
votes
2answers
241 views
Is every problem in NP?
My friend and I were studying NP-hard problems and NP-completeness. I don't think we have understood the concept very well so I thought I would come here to solve our doubt.
To show that a given ...
0
votes
0answers
605 views
Show that P is a subset of NP
Okay, before I start with the question I would like to point out that I am aware that there are many proofs of this question online. However, I am interested in showing this with the definitions of my ...
2
votes
1answer
32 views
Analysing the algorithm of a language called CONNECTED in Sipser to show that it belongs to class P
The question and its answer is given in the following picture:
But I do not understand why stage 2 causes at most $n+1$ repetitions, and why stage 3 uses at most $O(n^2)$ steps, and I understand that ...
1
vote
2answers
510 views
if traveling salesman problem is decidable in polynomial time, can an actual solution be proposed in polynomial time?
I'm asking because it seems that P problems refer to decision problems rather than actually propose a solution.
8
votes
0answers
218 views
Are there consequences for P ≠ NP that are unintuitive?
It's often regarded that the most intuitive answer to the question of $P$ vs $NP$ is that $P ≠ NP$. This is often illustrated with some consequences that would follow if $P = NP$ were true. Things ...
0
votes
0answers
24 views
NP-Hard for resolving P=NP [duplicate]
Im studing complexity theory and im reading this question on Quora.
According to what the guy is saying : if we are able to solve a NP-Hard problem in polynomial time we have prooved that P=NP.
But, ...
-3
votes
1answer
341 views
Could a scientist make money off of the P vs. NP solution?
If someone solved the P vs. NP problem, would they be able to keep it a secret and make money off of it by, say, starting a software or security company? Or would they only be able to publish it for ...
2
votes
1answer
239 views
Solving diophantine equations — does having a bound on the size of the solution help?
Let's define the following languages over the alphabet $\Sigma=\{0,1\}$:
H10 is the language of all strings that are encoding of diophantine polynomial equation with integer coefficients and $n$ ...
