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New
The latest blog posts to take off on Hacker News. 58 posts.
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How to determine if your A/B test is statistically significant
A/B testing tools often lie about whether something is "statistically significant." Here's an extremely simple, mathematically sound formula to compute it for yourself.
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World's shortest explanation of Gödel's theorem
From the highly eclectic blog of Mark Dominus
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Regular Expression Matching: the Virtual Machine Approach
Name the most widely used bytecode interpreter or virtual machine. Sun's JVM? Adobe's Flash? .NET and Mono? Perl? Python? PHP? These are all certainly popular, but there's one more widely used than all those combined. That bytecode interpreter is Henry Spencer's regular expression library and its many descendants.
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Beautiful plots of roots of polynomials
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…
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Step-by-Step Math
Have you ever given up working on a math problem because you couldn’t figure out the next step? Wolfram|Alpha can guide you step by step through the process of solving many mathematical problems, from solving a simple quadratic equation to taking the integral of a complex function.
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The 17x17 challenge. "Worth $289.00. This is not a joke."
The 17x17 challenge: worth $289.00. I am not kidding. Definition: The n x m grid is c-colorable if there is a way to c-color the vertic...
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Summary of all the MIT Introduction to Algorithms lectures
As you all may know, I watched and posted my lecture notes of the whole MIT Introduction to Algorithms course. In this post I want to summarize all the topics that were covered in the lectures and point out some of the most interesting things in them. Actually, before I wrote this article, I had started writing an...
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SciPy - the embarrassing way to code
I’ve programmed in many languages before, indeed I’ve spent at least a year working in Basic, C, C++, C#, java, assembler, modula-2, powerhouse and prolog. One thing I’ve never done before is Matlab, well except a few basic exercises for some course I did way back. A couple of years ago I started using python and more…
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How Credit Card Numbers Are Generated
Visa,Master Card,Discover, and American Express credit card validation and generation techniques using the luhn algorithm.
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Why I left math
Reading how shocked Doron Zeilberger is at the state of modern mathematics reminded me of why I left the subject. Math departments regularl...
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What every developer should know about time
How to handle time is one of those tricky issues where it is all too easy to get it wrong. So let's dive in.
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The Shocking State of Contemporary "Mathematics"
I just came back from attending the 1052nd AMS (sectional) meeting at Penn State, last weekend, and realized that the Kingdom of Mathematics is dead. Instead we have a disjoint union of narrow specialties , and people who know everything about nothing, and nothing about anything (except their very narrow acre). Not…
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The Busy Beaver Problem
Busy Beaver puts another one on the Turing Machine's tape (image from the book The New Turing Omnibus). The busy beaver problem is a fun theoretical computer science problem. Intuitively, the problem is to find the smallest program that outputs as many data as possible and eventually halts. More formally it goes…
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Functional Geometry
Peter Henderson wrote an article about a method to describe pictures with functional programs. I've implemented it in Lisp. An updated version of the article uses curves and different shapes and has some references to other applications for this method, like "An Algebra of Music".
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Intractability of Financial Derivatives
A new result by Princeton computer scientists and economists shows a striking application of computer science theory to the field of financial derivative design. The paper is Computational Complexity and Information Asymmetry in Financial Products by Sanjeev Arora, Boaz Barak, Markus Brunnermeier, and Rong Ge…
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The odd one out - inspired by IQ tests
Mathematics, applications of mathematics to life in general, and my life as a mathematician.
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Math Every Day
Math Every Day Stevey's Drunken Blog Rants™
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Teaching Linear Algebra
In a recent Hacker News post I made reference to an interesting teaching experience I had in the mid-90s. This is a longer explanation of ...
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The Three Projections of Doctor Futamura
Introduction The Three Projections of Futamura are a sequence of applications of a programming technique called 'partial evaluation' or 'sp...
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The New Science of Causation
It seems like each new day brings another one of those headlines: regular sleep “linked to” life expectancy, playing video games “associated with” surgical prowess, bullies “at risk” of becoming criminals, and “does breastfeeding reduce a baby’s blood pressure?” (the old rhetorical question gambit). Sometimes the…
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A bestiary of algorithmic trading strategies
One of the things which confronted me when I got interested in quantitative finance is the varieties of different kinds of quant. Now I realize this is pretty simple. Quants come in three basic var…
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Women Prefer Poaching
Men tend to want the woman they see in front of them, while women want the man other women see:
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