Are there any known W[3] or W[3]-hard problems?

We are currently working on a variant of domination parameter and we have shown that it is in W[3] with regard to parameterized complexity. To show it is W[3]-complete, we must show the problem is W[3] hard i.e, reduce an already known W[3] hard problem to ours. But unlike W[1] and W[2], where many famous problems are proved those classes, surprisingly we have not come across a single problem that is W[3] hard and not even in just W[3]. Of course there is the general W[t] case which we can go for, but any result for W[3] in particular would help a lot.

Proxy problems on windows 10


I tried to find a solution but in vain.

I have recently changed my PC which is running on windows 10 (x64).

After installing GSA SER, I pasted 100 private proxies. While testing proxies, all proxies are not verified, i.e., all proxies failed. 

On the other hand, I am using the same proxies on a VPS running on windows server 16 with GSA SER and they are running fine.

Therefore looking for help to configure windows 10 so that proxies should be tested properly.


Time computation problems with “Maximize” expression

I just started to use Mathematica a few weeks ago. I am afraid there is something that does not work on my laptop because, for the following simple command, it takes too much time. Do you know if there is a mistake in this command syntax? Thank you in advance for your help.

Maximize[{(g/e)*Sqrt[((g – e)^2 + (f – h)^2)], 0 <= e <= 1, 0 <= f <= 1, e^2 + f^2 == 1, 0 <= g <= e, 0 <= h <= f}, {e, f, g, h}]

Are there any unexpected problems with this Homebrew feat?

I (the DM) am considering the following feat, after a player asked about an alternative way to use Two Weapon Fighting.

Knife Fighter

You are especially skilled at the use of the Dagger, gaining the following benefits:

  • You gain a +1 bonus to AC while you are wielding a dagger.

  • You can use two-weapon fighting even when the one-handed melee weapon you attack with is not light, so long as the bonus attack is made with a dagger.

  • You can additionally draw or stow a dagger when you would normally be able to draw or stow any one-handed weapon.

  • You do an additional 2 damage when you hit with a dagger.

Obviously, the most direct comparison is to Dual Weilder. The intent of the feat is to allow a character to wield a Rapier and Dagger, or a pair of daggers and not be at a significant mechanical disadvantage over the Dual Wielder with a pair of rapiers.

Advantages I see compared to the Dual Wielder:

  • Marginally less expensive/heavy.
  • More concealable.


  • Additional damage is not multiplied on a critical hit.

Are there additional issues I have missed that would make this feat better or worse than Dual Wielder? Are the issues (above or otherwise) likely to cause problems or have interactions I have not forseen?

If a decision problem’s solution is exponentially large, then is it impossible for it to be in $NP$?

Decision Problem: Is $ 2^k$ + $ M$ a prime?

The inputs for both $ K$ and $ M$ are integers only. The solution is the sum of $ 2^k$ +$ M$ . (Use AKS to decide prime)

The powers of 2 have approximately $ 2^n$ digits. Consider $ 2^k$ where $ K$ = 100000. Compare the amount of digits in $ K$ to the amount of digits in it’s solution!


Could the solution be verified in polynomial time even though the solution is exponentially large?

If no, can I say it is not in $ NP$ ?

Problems with using a non-reserved top-level domain for local DNS resolution

A network administrator at my organization (let’s call him "Bill") wants to configure an internal DNS with the live top-level domain (TLD) .int for internal IP address resolution (for Active Directory, internal websites, etc.). For example, the domain would resolve to the some internal site that isn’t visible to the public. Our organization has not registered these domain names with a registrar. Now I know that this is bad practice, but Bill remains unconvinced that this shouldn’t be done.

What are the problems with using a live top-level domain for internal name resolution? Specifically, what are the security implications? In addition, does this somehow conflict with some fundamental way on how DNS and name resolution is supposed to work?

Note: I originally asked this question on Network Engineering SE and was kindly referred over to this site as a better place for this question.

Is it possible to train a neural network to solve NP-complete problems?

I’m sorry if the question is not relevant, i have tried to search for articles about it but i couldn’t find satisfying answers.

I’m starting to learn about machine learning, neural networks etc … and i was wondering if making a neural network that takes a graph as input, and output the answer of an np-complete problem (e.g. the graph is hamiltonian / the graph has independant set superior to k, and other decision problems) would work ?

I haven’t heard of any np complete problems being solved like this, so i guess it does not work, are there theoretical results stating that a neural network cannot learn np-complete language or something like this ?

How can we eliminate passwords given the problems with biometric authentication?

I’ve read articles suggesting that passwords will eventually go the way of the dinosaur only to be replaced by biometrics, PINs, and other methods of authentication. This piece claims that Microsoft, Google, and Apple are decreasing password dependency because passwords are expensive (to change) and present a high security risk. On the other hand, Dr. Mike Pound at Computerphile claims that we will always need passwords (I think this is the correct video).

But as this wonderful Security StackExchange thread notes, biometrics are not perfect. Granted, the criticisms are roughly six years old, but still stand. Moreover, and perhaps I have a fundamental misunderstanding of how biometric data is stored, but what if this information is breached? Changing a password may be tedious and expensive, but at least it can be changed. I’m uncertain how biometric authentication address this problem–as I cannot change my face, iris, fingerprint, and etc.–or if it needs to address this problem at all.

Are those who argue that we can eliminate passwords prematurely popping champagne bottles or are their projections correct?

Do any single-cell organisms exist that approximate NP-hard problems within a factor better than $1/2$ $log$2?

I’ve seen on Wikipedia; that set covering cannot be approximated in polynomial time to within a factor mentioned above. Unless $ NP$ has quasipoly-time algorithms.

Now, this must pertain to classical algorithms and does not mention any approximation algorithms that may only work in nature.

(eg. Things like Amoebas solving $ TSP$ problems)

  • Do any single-cell organisms show any promise in solving $ NP$ -hard problems in polynomial-time?

  • Or approximating them better than any known classical algorithms?