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The most popular blog posts about math & algorithms on Hacker News. 2,394 posts.
28 . That's the minimum number of AND or OR operators you need in order to write any Boolean function of five variables. Alex Healy and I computed that in April 2010. Until then, I believe no one had ever known that little fact. This post describes how we computed it and how we almost got scooped by Knuth's Volume 4A…
Meta Title: Math, Sports Data & IPTV: A Portugal Guide Meta Description: Explore how math-minded sports fans use IPTV in Portugal to watch live football, Champi
During WWII, statistician Abraham Wald told the RAF to add armor where it didn't seem planes needed it. But he was right.
I’m a stock market enthusiast 📈, so lately I have spent my spare time on the topic of stock option pricing, and I was curious to find out whether or not I could build a script that accurately reflected real market option prices. It turns out I came close, and learned a lot along the way, which I share in this article.
At Google, our organization designs, owns, and maintains a number of optimization models that automate the planning of Google’s datacenter growth and health. As is pretty standard in supply chain optimization and planning, these models are often integer linear programs. It’s a core competency of operations research…
Pathfinding is one of these topics that usualy baffles game developers. The A* algorithm in particular is poorly understood, and the general belief seems to be that it’s arcane magic.
Machine Alignment Monday, 7/24/23
Definition: The Fibonacci sequence is defined as \(F(0) = 0\), \(F(1) = 1\), and \(F(n) = F(n-1) + F(n-2)\) for \(n ≥ 2\). So the sequence (starting with \(F(0)\)) is 0, 1, 1, 2, 3, 5, 8, 13, 21, ….
Chess is a lot trickier than it looks. It has so many rules: castling, en passant, pawn promotion, pinning, the discovered check, and the de...
The space is divided into four rectangles . Each of those rectangles is divided such that it contains a maximum of four children . Each child is either a point or a smaller rectangle.
An image interpolation that gives us a continuous and smooth image, where every interpolated value only depends on the four neighboring pixel values. The image becomes smooth, but sharp features remain sharp.
From the highly eclectic blog of Mark Dominus
Experimenting with the "divisibility" of complex numbers, I stumbled across this thingy. It looks like a fractal. Although the formula does not do any iterations. It reminds me of something. But I dont know what. Doing a Google image search brings up a couple of galaxies :) This image shows the region from (-1/-1) to…
Have you ever found yourself in a situation where you had a bunch of parameters to tune for a better result, but there were just too many to exhaustively search all possibilities? I recently saw a …
The conventional wisdom is that hashing more entropy sources can't hurt: if H is any modern cryptographic hash function then H(x,y,z) is at least as good a random number as H(x,y), no matter how awful z is. So we pile one source on top of another, hashing them all together and hoping that at least one of them is good.
A brief introduction tutorial to Constraint Programming with Python, we introduce some relevant definitions and solve our old Pokémon Centers and Pokémon Gyms problem this time with CP!
Update 12/7/2012 @ 13:46: Peter Ferrie smashed my record by a single byte, so the record is now held by him at 12 bytes. Congrats, and I feel like a fool for missing it :-) I’ve tacked on h…
Some problems simply have no solution. Some problems have no simple solution. Some problems have many solutions. ...
The why and how of nonnegative matrix factorization Gillis, arXiv 2014 from: ‘Regularization, Optimization, Kernels, and Support Vector Machines.’ Last week we looked at the paper ‘Beyond news cont…
This is a brief continuation of a previous post ( Repo ), which introduced such visualization for collatz sequences based on Langton’s Ant .
Click on the picture for bigger view. Roots of quadratic polynomials are in grey; roots of cubics are in cyan; roots of quartics are in red and roots of quintics are in black. The horizontal axis of symmetry is the real axis; the vertical axis of symmetry is the imaginary axis. The big hole in the middle is centered…
<img src="http://stevehanov.ca/wavelet/cup.png"/> Let's say you have millions of pictures of faces tagged with names. Given a new photo, how do you find the name of person that the photo most resembles? <p> In the cases I mentioned, each record has hundreds or thousands of elements: the pixels in a photo, or patterns…
