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The most popular blog posts about math & algorithms on Hacker News. 2,391 posts.
These structures are so universal that most research papers in the theory of computation, programming languages and formal methods present concepts in terms of discrete mathematics rather than code.
A guide on how to generate sudokus of any difficulty.
If an expert can't understand your explanation, you've dumbed it down too much!
Why models always get better when they are bigger and deeper, even when the amount of data they consume stays the same or gets smaller.
I recently came across Paul Heckbert's business card raytracer. For those that have never heard of it: It is a very famous challenge in the Computer Graphics field that started on May 4th, 1984 via a post on comp.graphics by Paul Heckbert ( More about this in his article " A Minimal Ray Tracer " from the book Graphics…
A playable disease simulation
How to rotate an image, and a need trick to rotate a bitmap an arbitrary amount in a simple paint package.
On my Introduction to A* page I cover the basics of the A* graph search algorithm for finding shortest paths. Here’s an example from the town of Denerim in Dragon Age Origins. Try moving the start and goal to see A* in action:
We solve 20% of ARC-AGI-1 with no pretraining by minimizing the description length during inference time, with the only data involved being the target puzzle itself.
Inside every AI is a bigger AI, trying to get out
All original material on the geometry.org website is Copyright (C) 1999–2025, Alan U. Kennington.
This morning I had the pleasure to be a mathematical guest in my daughter’s third-grade class, full of inquisitive eight- and nine-year-old girls, and we had a wonderful interaction. Followin…
A data-driven exploration of how the Hacker News ranking algorithm works.
An interactive visualization to understand how neural networks work
If you, like me, frequently commute via public transit, you may be familiar with the following situation:
Math from Three to Seven: The Story of a Mathematical Circle for Preschoolers, Alexander Zvonkin (Moscow Center for Continuing Mathematical Education, 2007).
I wrote a little book about entropy; here’s the current draft: • What is Entropy? If you see typos and other mistakes, or have trouble understanding things, please let me know! An altern…
During some random discussion with my colleague today, I rediscovered an experiment I did quite some years ago: MP3 compression of image data. This is, feed raw 8-bit-per-pixel grayscale image data into an MP3 encoder, let it compress it, and decode the MP3 file again. After some conversion (the decoder will always…
" I think a lot of mathematics is really about how you understand things in your head. […]
Collaborative peer-to-peer applications sometimes need to operate on sequences of objects with a consistent order across all peers. For example, a peer-to-peer photo album application might need to sync the order in which photos appear in an album.
I decided to write an article about a thing that is second nature to embedded systems programmers – low level bit hacks. Bit hacks are ingenious little programming tricks that manipulate integers in a smart and efficient manner. Instead of performing operations (such as counting the number of 1 bits in an integer)…
In this course we explain how category theory—a branch of mathematics known for its ability to organize the key abstractions that structure much of the mathematical universe—has become useful for writing elegant and maintainable code. In particular, we'll use examples from the Haskell programming language to motivate…
Craig Gidney's computer science blog
Sweep-and-prune is my go-to algorithm when I want to quickly implement collision detection for a game. I think it’s an awesome and elegant algorithm, so I wrote a post about it.
Why does 0.1 + 0.2 = 0.30000000000000004?
