New arXiv preprint: we show algorithmic versions of the polynomial Freiman–Ruzsa (PFR) theorem of Gowers, Green, Manners, and Tao. Interestingly, our proof draws on quantum information and stabilizer learning algorithms, which we dequantize into classical algorithms.

arxiv.org/pdf/2509.02338

Fun facts: the Pizza theorem 🍕 states that if Alice and Bob cut a pizza in 4k slices (for k≥2) and take alternating slices, they'll get the same amount even if the cutting wasn't centered.

It was proven by Upton in 1968.

Before that, nobody knew how to cut pizza.
en.m.wikipedia.org/wiki/Pizza_t...

💡The first talks of the season are available!

- Prasanna Ramakrishnan, "How to Appease a Voter Majority"
- Or Zamir, "Optimality of Frequency Moment Estimation"
- Tom Gur, "A Zero-Knowledge PCP Theorem"
- Ryan Williams, "Simulating Time With Square-Root Space"

sites.google.com/view/tcsplus...

The introduction is also extremely fun to read!

📢 Our fourth TCS+ talk will be Wednesday, April 23 (10amPT, 1pm ET, 19:00 CEST): Ryan Williams (@rrwilliams.bsky.social), from MIT, will tell us about "Simulating Time With Square-Root Space"!

RSVP to receive the link (available one day prior to the talk):
forms.gle/hi9pBsgjRBMb... #TCSSky

I got a lot out of participating in WALDO back in 2021, so I definitely recommend checking it out! 😄

Bob* your calendar, as they say!

*Mark?

I'm a fan of this post!

Teaser: our first TCS+ of the season will be March 5 by Prasanna Ramakrishnan (Stanford), telling us "How to Appease a Voter Majority."

(We'd usually suggest cookies, lots of cookies 🍪 — but it turns out there is a better way!)

Mark the data: more details in the days to come!

New paper: Simulating Time With Square-Root Space

people.csail.mit.edu/rrw/time-vs-...

It's still hard for me to believe it myself, but I seem to have shown that TIME[t] is contained in SPACE[sqrt{t log t}].

To appear in STOC. Comments are very welcome!

There have been several remarkable developments in combinatorics, my field of mathematics. A few weeks ago I gave a talk to a general mathematical audience in which I described six breakthroughs from the last five years.

www.youtube.com/watch?v=726O...