Laurent Lessard

My contribution to the #Wordle discourse, with help from @VincentTjeng and @evanrsparks. A definitive look at the game: insights, heuristics, optimal strategies, and the limits of what is possible. laurentlessard.com/solving-wordle/

"Deadlines are final and no extensions will be given" You got me @IEEECDC2025 --- I totally fell for it! Happy April Fools everybody!

Can your AI keep up with dynamic attackers? In a paper to appear at #AISTATS2025 with @avibose22 @LaurentLessard and Maryam Fazel, we study robustness to learning algorithms to dynamic data poisoning attacks that can adapt attacks while observing the progress of learning

@gravity_levity It doesn't decay quite that quickly, but it's still fast: P(1) ~ 1/k! So basically: -log(P(1)) = O(k*log(k)) rather than: -log(P(1)) = O(k^2), which is what you had conjectured.

@LaurentLessard How does the probability decay with starting location k? Is it Gaussian at large k, P(1) ~ exp(-const.*k^2) ?

This week's #Fiddler puzzle is a random walk: From (k), you hop to (k-1) with probability 1/k and hop to (k+1) otherwise. If you start at (2), what is the probability you eventually hop to (1)? I wrote a short tutorial here: laurentlessard.com/bookproofs/can…

This week's #fiddler: Assign distinct prime numbers to the vertices of a dodecahedron so the sum of the vertices of each face sum to 2025. I modeled this as an integer linear program. Here is one possible solution. @xaqwg My write-up: laurentlessard.com/bookproofs/202…

Update: after 2 hours and 35 minutes on the tarmac, we are finally deplaning.

The pilot keeps saying there is "nothing he can do". You mean to tell me there are no other gates available at the airport? We can't deplane on the tarmac? This is a full flight with 8 seats across and we've been on this plane for almost 10 hours now.

Hey @AerLingus I'm on a flight from Dublin to Boston and we've been stuck on the tarmac at @loganairports after landing for TWO HOURS (and counting). Apparently other planes are being de-iced which is preventing us from deplaning...

This week's #Fiddler: what is the minimum-energy way to pack 9 particles in a square box, where energy is measured as the sum of 1/dist over all pairs of particles? Turns out it's NOT a regular 3x3 lattice! @xaqwg write-up: laurentlessard.com/bookproofs/par…

Halloween #fiddler puzzle: A bag contains N Reese's cups and an unknown number of candy corn pieces. You reach into the bag k ≤ n times at random and pull out a Reese's each time! How many candy corn do you expect to be in the bag? @xaqwg My write-up: laurentlessard.com/bookproofs/hal…

Great pleasure of hosting @LaurentLessard at USC who spoke about "An automatic system to detect equivalence between iterative algorithms" 🙂

@SpottedGeck @xaqwg Nice! You can approximate further using: Φ(x)-Φ(-x) ≈ 2x*Φ'(0) and you get: p(n) ≈ √6 / √(πn)

@xaqwg #scrollTo=0EcCHWcxdQXE" target="_blank" rel="nofollow noopener">colab.research.google.com/drive/1BWzQ0NH…

Rounds of rounding for #ThisWeeksFiddler by @xaqwg

@tom_keith1 And I believe this is the correct answer also! I derived it in my blog post x.com/LaurentLessard…

@tom_keith1 Relevant: oeis.org/A261398 This is the sequence of numerators, i.e. 2^n*n!*p(n)

#ThisWeeksFiddler by @xaqwg asks, how likely is it that n numbers rounded first and then summed equals the same numbers summed first and then rounded?

Thanks for reading! Let us know if you have any comments/questions!

One such example (we discuss others in the paper) is quasi-Newton methods. For these methods, line search serves the purpose of guaranteeing global convergence rather than finding a "best" step size. Once we enter a local convergence regime, adjustments are no longer beneficial.

New preprint with Joao Cavalcanti and @Ashia__Wilson! arxiv.org/abs/2408.13150 tl;dr: If you make your backtracking line search routine ADAPTIVE, you get faster continuous optimization algorithms with no additional computational burden! Longer summary below!🧵