Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Ask HN: What are you passionate about at the moment?

news.ycombinator.com

Post reply on HN
Print view View original

861–865 of 865 posts

Re: Ask HN: What are you passionate about at the moment?

#861

Post by a3_nm »

muldvarp wrote: post #206
a3_nm wrote: post #129

The following open research problem. Given an undirected graph G with two vertices s and t, the task is to determine whether there is an undirected path connecting s and t which is simple (no repeated vertices) and has length divisible by 3. It is not known whether this problem is NP-hard, or whether it can be solved in polynomial time; apparently the question is open since the early 90s. (The problem is also open fo…

What's the motivation for this problem if there is any? It's a really specific problem.

This came from a database theory study about queries on graphs: https://dl.acm.org/doi/10.1145/3517804.3524149 for the paywalled version, https://www.theoinf.uni-bayreuth.de/pool/documents/Paper2021... for the open-access paper. But honestly I find the problem intriguing for its own sake.

Re: Ask HN: What are you passionate about at the moment?

#862

Post by a3_nm »

sdenton4 wrote: post #145
a3_nm wrote: post #129

The following open research problem. Given an undirected graph G with two vertices s and t, the task is to determine whether there is an undirected path connecting s and t which is simple (no repeated vertices) and has length divisible by 3. It is not known whether this problem is NP-hard, or whether it can be solved in polynomial time; apparently the question is open since the early 90s. (The problem is also open fo…

An old favorite open graph theory problem: In your right hand, take any collection of trees with 2, 3, ..., n vertices. These have a total of 1+2+...+n-1 edges, ie, n choose 2. In your left hand, take the complete graph with n vertices. This, of course, has the same number of edges. Conjecture: it is always possible to pack/embed the trees into the complete graph in such a way that all edges are matched exactly once.…

Interesting! It looks like this is called the "Gyárfás tree packing conjecture".

Re: Ask HN: What are you passionate about at the moment?

#863

Post by polivier »

mzl wrote: post #857
polivier wrote: post #605

Earlier quoted context omitted.

The problem mentioned in the Gecode documentation example is different than the one I solve. In their case, they start with a WxH grid with known black square positions, and their model essentially answers the following question: "Given a crossword grid template and word list, does there exist a feasible assignment of words for the template?" I my case, the black square positions are unknown, so the question instead…

Just saw that it looks like an upcoming release of OR-Tools might include reified tables: https://github.com/google/or-tools/commit/94f3d9b46870e7ea04...

Yes, Laurent was nice enough to add this feature. I'm curious to see the difference in performance this will have over the workaround that I used.

Re: Ask HN: What are you passionate about at the moment?

#864

Post by ProllyInfamous »

monero-xmr wrote: post #85
ProllyInfamous wrote: post #70

Earlier quoted context omitted.

I've been a crypto_saver for over a decade; yet still I downvoted your ridiculousness [parent comment]. Please don't be so wreckless in your passion(s). And: HODL

I've been yield farming for years, this is not a new thing.

Great username. Currently heating my personal home primarily with xmr-rig.

I have a heatpump, but why?! /s

Re: Ask HN: What are you passionate about at the moment?

#865

Post by cambaceres »

solardev wrote: post #7

There is a new show on HBO called Scavengers Reign, and it's become my favorite scifi story ever. https://www.imdb.com/title/tt21056886/ It's kinda like watching Planet Earth about another ecosystem, with a strong focus on judgment-free ecology (ie there isn't good and evil, just different flora and fauna and otherwise interacting both with their normal food webs and with human outsiders). It really tickles the envir…

Hi, I read your comment last week and now I've almost completed the show, I love it. Do you have any other recommendations?
Post reply on HN