Recent advances in computer science since 2010?
Since I left school (early 2010s) a couple of recently developed techniques were widely adopted by the industry. For example, Asymmetric numeral systems for compression (e.g. Ubuntu ships with zstd command line utility which implements ideas from ANS). Raft consensus algorithm for consensus in distributed systems, implemented in many widely used systems such as etcd. are some recent advances in co
CompCert - Main page
The CompCert project investigates the formal verification of realistic compilers usable for critical embedded software. Such verified compilers come with a mathematical, machine-checked proof that the generated executable code behaves exactly as prescribed by the semantics of the source program. By ruling out the possibility of compiler-introduced bugs, verified compilers strengthen the guarantees
x + 0.25 - 0.25 = xが成り立たないxとは何か｜Rui Ueyama
スタンフォードのコンピュータサイエンスの授業で、ときどきこれは良問と思う問題がテストで出ることがある。僕の印象に残っているのは「xをfloatとするとき、x + 0.25 - 0.25 = xが成り立たないxを求めよ」というものだ。浮動小数点数を理解していないと、両辺が同じにならないケースがあるほうが不自然に思えるだろうから、この問題は浮動小数点数の奇妙さを結構うまく突いていると思う。この問題を元に浮動小数点数についてちょっと説明してみよう。 まずコンピュータ上での数について少し考えてみよう。コンピュータにおける数と、数学の整数や実数は、よく考えてみると全然違う。コンピュータは有限の記憶領域しか持っていないので、無数にある数を表すことが根本的にできない。つまりコンピュータ上の数は「本物の数になるべく似せた別の何か」だ。現実的には、例えば32ビットの数なら2^32パターンしか表せないので、そ
Faster big-data analysis
We live in the age of big data, but most of that data is “sparse.” Imagine, for instance, a massive table that mapped all of Amazon’s customers against all of its products, with a “1” for each product a given customer bought and a “0” otherwise. The table would be mostly zeroes. With sparse data, analytic algorithms end up doing a lot of addition and multiplication by zero, which is wasted computa
Floating Point Visually Explained
While I was writing the Wolfenstein 3D book[1], I wanted to demonstrate how much of a handicap it was to work without floating points. My attempts at understanding floating points using canonical[2] articles[3] were met with resistance from my brain. I tried to find a different way. Something far from $(-1)^S * 1.M * 2^{(E-127)}$ and its mysterious exponent/mantissa. Possibly a drawing since they
From design patterns to category theory
How do you design good abstractions? By using abstractions that already exist. When I was a boy, I had a cassette tape player. It came with playback controls like these: Soon after cassette players had become widely adopted, VCR manufacturers figured out that they could reuse those symbols to make their machines easier to use. Everyone could play a video tape, but 'no one' could 'program' them, be
Shor, I’ll do it
The Blog of Scott Aaronson If you take nothing else from this blog: quantum computers won't solve hard problems instantly by just trying all solutions in parallel. And also: deliberately gunning down Jewish (or any) children is wrong. I’ve been talking a lot recently about how quantum algorithms don’t work. But last week JR Minkel, an editor at Scientific American, asked me to write a brief essay
Voronoi Tessellations
Newsletter: Click here to join an email list and be contacted when a new article is published. Advertisement This week I’m going to talk about Voronoi diagrams. These constructions are really pretty, and simple to explain. Imagine I’m in a desert, and there are two wells where I can obtain water. If I want to go to the nearest well, which well do I visit? Clearly, it depends one where I am standin
On The Turing Completeness of PowerPoint (SIGBOVIK)
Video highlighting my research on PowerPoint Turing Machines for CMU's SIGBOVIK 2017 Read the paper: http://tomwildenhain.com/PowerPointTM/Paper.pdf Download the TM: http://tomwildenhain.com/PowerPointTM/PowerPointTM.pptx Original video (without live background noise): https://youtu.be/sdkxWqsk17c Music: The Land Of The Wizard by Machinimasound licensed under Creative Commons Attribution 4.0
私たちはいかにして環状線で”悪さをする列車”を捕まえたか | プログラミング | POSTD
文：Daniel Sim 分析：Lee Shangqian、Daniel Sim、Clarence Ng ここ数ヶ月、シンガポールのMRT環状線では列車が何度も止まるものの、その原因が分からないため、通勤客の大きな混乱や心配の種となっていました。 私も多くの同僚と同じように環状線を使ってワンノースのオフィスに通っています。そのため、11月5日に列車が止まる原因を調査する依頼がチームに来た時は、ためらうことなく業務に携わることを志願しました。 鉄道運営会社SMRTと陸上交通庁（LTA）による事前調査から、いくつかの電車の信号を消失させる信号の干渉があり、それがインシデントを引き起こすことが既に分かっていました。信号が消失すると列車の安全機能である緊急ブレーキが作動するため、不規則に電車が止まる原因となります。 しかし8月に初めて発生した今回のインシデントは、不規則に起こっているように見えるた
Blockchain Demo
by Anders Brownworth BTC: 1K3NvcuZzVTueHW1qhkG2Cm3viRkh2EXJp ETH: 0x84a90e21d9d02e30ddcea56d618aa75ba90331ff
Herbie Automatically Improving Floating Point Accuracy
Herbie detects inaccurate expressions and finds more accurate replacements. The red expression is inaccurate when x > 1; Herbie's replacement, in blue, is accurate for all x. Herbie improving accuracy on the “Hamming” benchmark suite. Longer arrows are better. Each arrow starts at the accuracy of the original expression, and ends at the accuracy of Herbie’s output, in each case on random double-pr
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Joe Groff on Twitter: "Pack it in, mathematicians, someone owes LLVM a million bucks https://t.co/u7DYMBwqFE https://t.co/wJRC6LWOyA"
Galois Field in Cryptography
Amazon.co.jp: グッド・マス ギークのための数・論理・計算機科学: Mark C. Chu‐Carroll (著), cocoatomo (翻訳): 本
Mercedes Euklid
https://github.com/papers-we-love/zurich/blob/master/2017.06.29-Raft/pwl-raft-trivedi.pdf
Lecture 16: NP and PSPACE Video Games | Algorithmic Lower Bounds: Fun with Hardness Proofs | Electrical Engineering and Computer Science | MIT OpenCourseWare
「ブロックチェーン」ってなに？ 社会変えるか注目の技術 - Yahoo!ニュース
Scheduling Algorithms in Big Data: A Survey Nagina, Dr. Sunita Dhingra