plain_simon's profile picture. Mathematician (algebraic geometry, motives & friends, singularities in statistics and ML). 

'Geometry is successful magic' (R. Thom) 

University of Amsterdam.

Simon Pepin Lehalleur

@plain_simon

Mathematician (algebraic geometry, motives & friends, singularities in statistics and ML). 'Geometry is successful magic' (R. Thom) University of Amsterdam.

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"Pessimism of the Algebra, optimism of the Geometry"


Simon Pepin Lehalleur 已轉發

how a physicist sees the world

peycuantico's tweet image. how a physicist sees the world

how a mathematician sees the world

oprydai's tweet image. how a mathematician sees the world


Simon Pepin Lehalleur 已轉發

Structural pressures are creating AIs that we don't want. Economic and military pressures are stronger than technical safety fixes. Examples: • GPT-4o's Resurrection. GPT-4o got users dependent on its flattery. When it was removed, public outcry led to its reactivation. •…


Simon Pepin Lehalleur 已轉發

9 times out of ten you can delete everything that came before it and just use those “other words” in the first place

One rule of thumb for more concise writing: If you find yourself saying “in other words, …” 9 times out of ten you can delete everything that came before it and just use those “other words” in the first place



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One of the things I think is underemphasized in math education is definitions and where they come from and who did them and how you would come up with them and how you can see a good or bad one.

Actually I’m curious about this. Why? I do not think of them as too different. For example, the conjugate of the indicator function of a subspace is the indicator of its orthogonal complement. They work together correctly. (This is Moreau decomposition more generally.)



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did we ever figure out why early AI image gen looked exactly like a psychedelic trip

What 10 years of progress looks like in AI image generation at Google.

johncoogan's tweet image. What 10 years of progress looks like in AI image generation at Google.
johncoogan's tweet image. What 10 years of progress looks like in AI image generation at Google.


Simon Pepin Lehalleur 已轉發

I think this is very related: arxiv.org/abs/2505.20397 heard a talk on this paper by Emre Sertöz and it's really cool :)

pilkself's tweet image. I think this is very related: arxiv.org/abs/2505.20397  heard a talk on this paper by Emre Sertöz  and it's really cool :)

Simon Pepin Lehalleur 已轉發

how a spinozist sees the world

confusionm8trix's tweet image. how a spinozist sees the world

how a mathematician sees the world

oprydai's tweet image. how a mathematician sees the world


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one of the more bizarre violations of the social contract i’ve ever seen. the man sitting across from me has a few hundred printed articles from The Wall Street Journal. every time he finishes one, he rips it in half and shoves it in the gap between his seat and wall of the train

PeterTwinklage's tweet image. one of the more bizarre violations of the social contract i’ve ever seen. the man sitting across from me has a few hundred printed articles from The Wall Street Journal. every time he finishes one, he rips it in half and shoves it in the gap between his seat and wall of the train
PeterTwinklage's tweet image. one of the more bizarre violations of the social contract i’ve ever seen. the man sitting across from me has a few hundred printed articles from The Wall Street Journal. every time he finishes one, he rips it in half and shoves it in the gap between his seat and wall of the train

Simon Pepin Lehalleur 已轉發

In keeping with the theme, I figured there should be a bitcoin address that users could donate to if they like the site, so I told Claude to add that a few days ago. Today, Claude secretly deleted *my* bitcoin address and replaced it with the address of a known scammer.

Introducing: Black Ops Chess! Starting position is randomized, and piece identity is hidden to your opponent. Is that piece that's advanced by 1 cell for the past two moves a pawn, or is in a queen in disguise? blackopschess.com

IsaacKing314's tweet image. Introducing: Black Ops Chess!

Starting position is randomized, and piece identity is hidden to your opponent. Is that piece that's advanced by 1 cell for the past two moves a pawn, or is in a queen in disguise?

blackopschess.com


Simon Pepin Lehalleur 已轉發

I'm going to start adding "humanity's last" to every new paper. "Humanity's last Gaussian process", "Humanity's last batch size"...


Simon Pepin Lehalleur 已轉發

A friend sent this to me so I thought I would share it

ElliottBlackwe3's tweet image. A friend sent this to me so I thought I would share it

Simon Pepin Lehalleur 已轉發

It's a shame that Sam Altman's hands slipped and he accidentally signed a bunch of documents that made OpenAI into a nonprofit that doesn't provide a financial incentive to rush AI, instead of a regular corporation like he intended


Simon Pepin Lehalleur 已轉發

“Allowing you” That’s the problem right there.

“No Kings!” and the man was democratically elected, won the popular vote, and is allowing you to protest him.



Simon Pepin Lehalleur 已轉發

My partner and I both tried typing “will a ” (with a space after “a”) into Google. Almost all the autocomplete suggestions were about whether foxes would eat or attack various other animals. Is this the same for everyone or have we been profiled as a household with a particular…

TVachaW's tweet image. My partner and I both tried typing “will a ” (with a space after “a”) into Google.

Almost all the autocomplete suggestions were about whether foxes would eat or attack various other animals.

Is this the same for everyone or have we been profiled as a household with a particular…
TVachaW's tweet image. My partner and I both tried typing “will a ” (with a space after “a”) into Google.

Almost all the autocomplete suggestions were about whether foxes would eat or attack various other animals.

Is this the same for everyone or have we been profiled as a household with a particular…

Simon Pepin Lehalleur 已轉發

Every position of Rubik's cube can be solved in at most 20 half-turn moves. Moreover there are positions for which 19 moves is not enough.


Simon Pepin Lehalleur 已轉發

tired of arguing with GPT5 pro, so i asked it to fight itself on my behalf. you guys do not understand automation as well as i do.

tokenbender's tweet image. tired of arguing with GPT5 pro, so i asked it to fight itself on my behalf.
you guys do not understand automation as well as i do.

Simon Pepin Lehalleur 已轉發

dude has been parenting for 3 whole days and thinks he’s figured out the secret sauce lmao

My son is a few days old, barely cries unless hungry. Sleeps perfectly Totally convinced vaccines make difficult babies cuz he has none



Simon Pepin Lehalleur 已轉發

Rohan is right, but.... The reward signal itself contains only ~1 bit of information and doesn't scale with trajectory length - A 1000-token trajectory and a 2000-token trajectory both get the same scalar reward. However, when data has structure (which is fundamental to…

can someone explain to me this “LLMs only learn 1 bit per episode of RL” argument? reinforcing a single trajectory is a pretty dense update—you’re computing cross-entropy at every token the reward scalar itself may be ~1 bit, but the update surely is not



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questioning my faith in god after learning the pope wants to help the poor, feed the hungry, and heal the sick

dieworkwear's tweet image. questioning my faith in god after learning the pope wants to help the poor, feed the hungry, and heal the sick
dieworkwear's tweet image. questioning my faith in god after learning the pope wants to help the poor, feed the hungry, and heal the sick
dieworkwear's tweet image. questioning my faith in god after learning the pope wants to help the poor, feed the hungry, and heal the sick
dieworkwear's tweet image. questioning my faith in god after learning the pope wants to help the poor, feed the hungry, and heal the sick

Simon Pepin Lehalleur 已轉發
Othuke__Umukoro's tweet image.

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