NP-hard problems (Non-deterministic Polynomial-time hard problems) are those problems which are not easier than any problem in NP; in other words, an algorithm for an NP-hard problem can be used to solve any problem in NP by transforming the input in polynomial time. Problems which are in both NP-Hard and NP are known as NP-Complete.
Questions tagged [np-hard]
178 questions
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Maximizing profit in graph having positive weight cycles
I have a set of vertices with some profit defined between each pair of vertices such that profit(i,j) may not be equal to profit(j,i). Moreover there exist positive weight cycles and the profit may be negative.
This is a NP-hard problem to find the…
Shashwat Kumar
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When NP complete becomes NP hard
Generally, assuming we have a NPC problem. Adding more constraint to it (making it more difficult), is it possible that problem become NPH? I know the difference between NPC and NPH but I don't know how to show that adding new constraints to…
Sara
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Np completeness - Need some clarification in reduction
I wanted some clarification in a concept.
For proving that a problem is NP complete, we use reductions.
Now suppose I have L<=L'. has the reduction to be from L to L' or can I do it it the reverse way also? i.e Can I show that if L can be solved…
Aakash Anuj
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Can it be proven no polynomial algorithm exists for an NP-Complete prob.?
I can't really seem to grasp what it really means to say a problem is NP-Complete. Could anyone help me with the following question?
An NP-complete problem is a problem for which one can prove that an algorithm for solving it in polynomial time does…
StayPuff
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proof of SAT np completeness
I know if we want to prove the np completeness of some problem we must show these :
there is a nondeterministic polynomial solution for the problem
all other np problems are reducible to the problem
in the case of sat problem it's easy to show…
Mohsen Liaghat
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Is this assignment problem with constrains NP-hard?
It is a many-to-one assignment problem with N tasks and M people.
Each person can get multiple tasks, while each task can be assigned to only one person. We can earn a profit Pij if the task i is assigned to person j.
If T1, T2, ... , Tm is a…
Oscar
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Classifying NP Completeness and Hardness
Choose the correct statement(s):
(A) If X is an NP-complete problem, then X is an NP problem
(B) If X is an NP-complete problem, then X is an NP-hard
(C) Let X be an NP-complete problem. If X can polynomial reduce to a problem Y, then Y is an…
ILiketoaskQuestion
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Maximizing the overall sum of K disjoint and contiguous subsets of size L among N positive numbers
I'm trying to find an algorithm to find K disjoint, contiguous subsets of size L of an array x of real numbers that maximize the sum of the elements.
Spelling out the details, X is a set of N positive real numbers:
X={x[1],x[2],...x[N]} where…
Raman
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example of reduction a polynomial decision to an NP-complete
I know if I reduce an NP-complete problem to a unknown problem P then I'm sure that P is itself NP-complete. And I know if I reduce a Problem P to an NP-complete problem there is no conclusion. So I want to give an example to show that we can reduce…
user3070752
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np-hard -closure
if l1 is in NP-HARD, so for every L2!=empty set, l1*l2 is in np-hard.
when:
l1*l2={(w1,w2) , w1 in L1 and w2 in L2}
Is it true or false and why?
I can't approve it but I also don't find counter example.
user1462787
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NP-hard algorithm
I'm working on a NP-hard problem algorithm (like hand seller problem) and I can't find the proper algorithm. I will appreciate if anyone can help me with it. We have a (x,y) matrix, there is a robot in the (n,m) block and there are some rubbish in…
ali khorshidi rozbahani
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Is there any NP example that we can get an answer in polynomial time？
I just read NP and P on wikipedia, I have two questions:
Can we solve an NP example in polynomial time ?
Is there any NP example that we can get an answer in polynomial time？
Tracy Da
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Java: Traveling Salesman - Found polynomial algorithm
Edit: An improvement to this algorithm been found. Your are welcome to see it.
This question is the an improvement of my old question. Now I want to show you Java code sample, and explain my algorithm in more details.
I think that I found a…
Ilya Gazman
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