StevenXC (u/StevenXC)

StevenXC commented on National Institutes of Health cuts support to universities arstechnica.com/science/2... · Posted by u/dangle1

dekhn · a year ago

When I was an academic, I did all my work in the cloud. I didn't use copy paper, or even really need to be in the office (it had slower networking, and less comfortable chairs). The university had a multi-billion dollar endowment and got billions from the state to run its educational mission. Why should I be raising 50% on top of my money (which was so high, NIH often wanted to give money to people at "cheaper" universities).

StevenXC · a year ago

It's very unclear to me how you seem to expect medical research to be done in the cloud. Overhead is crucial to create and maintain research infrastructure necessary to advance medicine and science.

StevenXC commented on Teachers: AI is making children dumb as fuck old.reddit.com/r/Teachers... · Posted by u/Onavo

StevenXC · 2 years ago

I wrote a small novel but lost it due to user error, so here's a hot take with much less nuance from a college math professor. Just like calculators meant we needed and could pivot the skills we ask our students to learn, AI will also shift the paradigm. But unlike calculators, which are very good at what they're meant to do, AI produces BS in the academic sense [0] and if used uncritically frequently produces work that's just nonsense. So I tell students I don't care so much if they use it, but that the students who do tend to end up looking foolish.

[0]: https://link.springer.com/article/10.1007/s10676-024-09775-5

StevenXC commented on Why is x & -x equal to the largest power of 2 that divides x? arunmani.in/articles/high... · Posted by u/arun-mani-j

dataflow · 2 years ago

Short explanation:

1. The largest power of 2 that divides x is just 2^(number of trailing zeros in x)

2. Crucial observation: -x == ~x + 1

3. ~x flips all the bits of x bits, so none of the bits of ~x match those of x. (i.e. (x & ~x) == 0)

4. When you do +1, all the trailing 1's flip AGAIN, becoming zero like they were in x. The next highest 0 (say it was the n'th) also flips, becoming 1... like it was in x.

5. Crucial observation: The n'th 0 did NOT match the corresponding bit in x prior to the increment, therefore it MUST match after the increment. All higher bits stay as-is.

6. This leaves only the n'th bits matching in x and ~x + 1, isolating the highest power-of-2 divisor of x when you AND them.

StevenXC · 2 years ago

Algebraically, where | denotes concatenation, and z is a string of 0s:

x = y | 1 | z

-x = ~x + 1

-x = (~y | 0 | ~z) + 1

-x = ~y | 1 | z

x & -x = (y & ~y) | (1 & 1) | (z & z)

x & -x = 0 | 1 | z

Deleted Comment

StevenXC commented on Mathematicians and the Selection Task (2004) eric.ed.gov/?id=ED489556... · Posted by u/tzs

StevenXC · 2 years ago

As an math educator, I think there's a huge flaw in this study. The investigators failed to follow up to see why the mistake was made. They leap to assuming the player is trying to "deny the antecedent", but I think there's a much simpler explanation: the players aren't reading the instructions carefully.

There's two reading errors I would expect someone to make given this experiment:

1. The instructions that each card has exactly one letter and exactly one number are before the big cards. I bet many players just skipped that instruction.

2. Mistaking the P→Q as P←→Q smacks more of a reading comprehension error than a logical error.

Disclosure: I made both mistakes. (-:

StevenXC commented on I organized a 20-acre game of Capture the Flag ntnbr.com/61/... · Posted by u/ntnbr

StevenXC · 2 years ago

the kids are alright. Reminds me of when I organized a real life version of Pac-Man on the quad in 2006, inspired by this game ran on the streets of Manhattan in 2004. https://www.pacmanhattan.com/

StevenXC commented on Putting a Wet Towel on a Tesla Supercharger Handle Gets Faster Charging Speeds insideevs.com/news/718718... · Posted by u/peutetre

pfdietz · 2 years ago

All these people being wet blankets on this idea. I'm shocked, shocked.

StevenXC · 2 years ago

It's just a little spark of inspiration.

StevenXC commented on Stack Overflow users deleting answers after OpenAI partnership build5nines.com/stack-ove... · Posted by u/miles

kragen · 2 years ago

> if any of the super answerers really wanted, they could have tried to sue for illegally making their answers available under a different license.

they can plausibly sue people other than stackoverflow if they attempt to reuse the answers under a different license. but i think it's very difficult to find a use that 4.0 permits that 3.0 doesn't

StevenXC · 2 years ago

3.0 has a "bug" that makes it risky to use materials without very careful attribution:

https://doctorow.medium.com/a-bug-in-early-creative-commons-...

StevenXC commented on U-M finds students with alphabetically lower-ranked names receive lower grades record.umich.edu/articles... · Posted by u/cebert

zdw · 2 years ago

As someone whose initials are Z and W, I tend to notice alpha sort a lot. Asking a friend whose initials are A and B about this, it's not something they ever noticed.

I haven't noticed a grading/ranking difference, but far more frequently I'll hear that "oh, we ran out of item/time/etc. before we got to you", which has made me much more sensitive to issues of planning/organization.

StevenXC · 2 years ago

Like most inequities, those who are in the benefiting group frequently don't realize that privilege.

StevenXC commented on Math Puzzles jrmf.org/puzzle/... · Posted by u/mooreds

StevenXC · 2 years ago

Nice to see JRMF trending on HN. JRMF puzzles and festivals are a great way to engage general audiences of grade school students in mathematical inquiry and problem solving.

u/StevenXC

KarmaCake day224December 6, 2012View Original