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Laurent Lessard

@laurentlessard

Associate Professor of MIE @Northeastern. Interested in control theory, optimization, math, and puzzles. The glass is twice as large as it needs to be.

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12.11.2024
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Latest posts by Laurent Lessard @laurentlessard

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Using* the most cursed #ALevelMaths Formula in #MathsToday

*absolutely not using but fun as a hook for Radians Sector lesson with Y12

11.06.2025 18:52 πŸ‘ 21 πŸ” 7 πŸ’¬ 4 πŸ“Œ 0
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30.01.2025 23:47 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Wow. it must feel terrible when someone takes something you made and uses it without permission or payment

29.01.2025 04:59 πŸ‘ 18971 πŸ” 5075 πŸ’¬ 181 πŸ“Œ 84
Can you hop to the lily pad? - Book Proofs This week's Fiddler is about hopping back and forth. You are a frog in a pond with an infinite number of lily pads in a line, marked "1," "2," "3," etc. You are currently on pad 2, and your goal is to...

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)? @xaqwg.bsky.social

I wrote a short tutorial here:
laurentlessard.com/bookproofs/c...

26.01.2025 20:31 πŸ‘ 5 πŸ” 1 πŸ’¬ 0 πŸ“Œ 0
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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.bsky.social

My write-up: laurentlessard.com/bookproofs/2...

22.12.2024 20:13 πŸ‘ 8 πŸ” 2 πŸ’¬ 0 πŸ“Œ 0

Print your pdf to pdf and then try again! Seriously!

13.12.2024 20:24 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

More fun: if you assume the energy function is 1/r^k, then the regular lattice is optimal for k > 1.067 and the irregular arrangement is optimal for k < 1.066. πŸ€·β€β™‚οΈ

09.12.2024 01:03 πŸ‘ 1 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0

Interestingly, if energy is instead measured as 1/distΒ², then the regular lattice becomes the optimal arrangement!

09.12.2024 00:37 πŸ‘ 2 πŸ” 0 πŸ’¬ 0 πŸ“Œ 0
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This week's #Fiddler: what is the minimum-energy way to pack 9 particles in a unit square, 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.bsky.social

write-up:
laurentlessard.com/bookproofs/p...

09.12.2024 00:29 πŸ‘ 7 πŸ” 1 πŸ’¬ 2 πŸ“Œ 0