Henrik A. Friberg

Mathematical optimization enthusiast and part of the R&D team at MOSEK ApS.

[Henrik A. Friberg @HAFriberg]

https://t.co/Cfl8XfxgEk

[Henrik A. Friberg @HAFriberg]

Follow me on BlueSky where I have started tweeting. A link to my profile can be found in the replies.

[Henrik A. Friberg @HAFriberg]

Nice to see developments in this field - great math. Not sure the benchmark is all that reliable though, as they report 60 ms projection times, as opposed to the 6 μs I was observing. That is a 10'000x difference on similar hardware!?

[arXiv math.OC Optimization and Control @mathOCb]

Luis M. Brice\~no-Arias, Crist\'obal Vivar-Vargas: Projection onto cones generated by epigraphs of perspective functions https://t.co/BngqIxSsQY https://t.co/S8NCG1AhBY

[Henrik A. Friberg @HAFriberg]

@kareem_carr To my belief, his creativity--attributed to dreaming--were not in predicting formulas like a chatgpt, but in his use of nonstandard math to manipulate infinite sums and continued fractions in novel ways.

[Henrik A. Friberg @HAFriberg]

@_Hexaly Is Hexaly competitive with Concorde on TSP?

[Tobias Achterberg @AchterbergT]

MIPLIB 2024 submissions open: https://t.co/CIbJGJO4NU
Submit all instances you can share!
Closes: 30.11.2024
Restrictions: Mixed-integer linear programs (includes integer programs + indicator / SOS constraints).

[Henrik A. Friberg @HAFriberg]

@Anthony_Bonato In (g), why not be precise and say *exactly* one solution?

[Henrik A. Friberg @HAFriberg]

@pickover In other words, f(2) = 2, but
f(2.1) = 2.2
f(f(2.1)) = 2.57
f(f(f(2.1))) = 4.67
f^4(2.1) = -1.2
f^5(2.1) = 0.47
f^6(2.1) = 0.79
...,
f^11(2.1) = 0.99,
f^∞(2.1) = 1

[Henrik A. Friberg @HAFriberg]

@pickover The function f(x) = 2 / (3-x) has two fixed points; 1 is an attractor (stable solution) and 2 is a repellent (unstable solution).

[Henrik A. Friberg @HAFriberg]

@pickover All primes are π-primes?

[Henrik A. Friberg @HAFriberg]

Getting ready for https://t.co/R4qNO4mLcf, writing a paper to elaborate a note in my slides:
https://t.co/svyyZQlREE

Hope to see you all!

[Henrik A. Friberg @HAFriberg]

Sound propagates at around 300 m/s.
Light propagates at around 300 m/μs.
(air speeds near earth; 1 significant digit of precision; beautiful and memorable)

[Henrik A. Friberg @HAFriberg]

@VictorTaelin There are plenty of algorithms out there to do reasoning. GPT just needs to compose a prompt for one of these tools and map the result back in the language of the problem.

[Henrik A. Friberg @HAFriberg]

@MeTheDeluge @littmath Interestingly, Bob has an advantage if the final toss is H (such that the last sequence is interrupted prematurely) because his EV has larger partial sums. That is, sum_(i=1)^n (1/2^i - (i-1)/2^i) > 0 for finite n.

[Henrik A. Friberg @HAFriberg]

@MeTheDeluge @littmath You mean 0*1/2 + 1*1/4 + 2*1/8 + … approaching 1 for Alice. It is <1 for a finite game, but so it is for Bob because the game may end before the sequence

[Henrik A. Friberg @HAFriberg]

@sonukg4india Step 3 notation 😭 Show me a calculator that says ln(e)^2 = ln(e*e) = ln(e)+ln(e) = 1+1 = 2.

[Henrik A. Friberg @HAFriberg]

@themarklstone No cutting, no pizza, but I recognize the issue. In this house one will eventually take the knife and it can take several cuts just to make two equal portions.

[Henrik A. Friberg @HAFriberg]

Let child 1 decide on a fair cut into n pieces and let children 2,…,n pick their favorites. Child 1 gets the leftover, and the other n-1 pieces are put back in the middle. Now it’s child 2 to cut and get the leftover, and so it repeats until the utility has been distributed.

[Subject to @Subjectto_]

Nice post by Ken Fordyce on Linear Programming, shared on the INFORMS Open Forum and partially inspired by Bob Bixby's s.t. episode:

https://t.co/wds3Un1Ylh

[Henrik A. Friberg @HAFriberg]

@PVanHentenryck The answer is bootstrapping: https://t.co/DVopQGLbF9. Start with a very limited and simple checker that is pain to write programs for, but easy for humans to understand. Use it to validate a more advanced checker that is less restrictive. Repeat until practically useful.