Communications of the ACM
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How the “Frontier” Became the Slogan of Uncontrolled AI
Artificial intelligence (AI) has been billed as the next frontier of humanity: the newly available expanse whose exploration …
From Daniel Lemire's Blog
How Innovation Works (book review)
I read How Innovation Works by Matt Ridley in a few hours. It is a delicious book. Ridley distinguishes invention from innovation. The inventor creates something...
From Daniel Lemire's Blog
The Go compiler needs to be smarter
One of my favorite languages is the Go language. I love its simplicity. It is popular and useful in a cloud setting. Many popular tools are written in Go, and for...
From Daniel Lemire's Blog
Science and Technology links (May 30th 2020)
We might soon be able to buy memory cards with speeds nearing 4 GB/s. For comparison, an expensive and recent macBook currently has a disk with a 2 GB/s bandwidth...
From Daniel Lemire's Blog
Mapping an interval of integers to the whole 64-bit range, fairly?
In my blog post A fast alternative to the modulo reduction, I described how one might map 64-bit values to an interval of integers (say from 0 to N) with minimal...
From Daniel Lemire's Blog
Programming inside in a container
I have a small collection of servers, laptops and desktops. My servers were purchased and configured at different times. By design, they have different hardware...
From Daniel Lemire's Blog
Science and Technology links (May 16th 2020)
Most of our processors, whether in our PCs or mobile phones, are 64-bit processors. In the case of your PC, it has been so for a couple of decades. Unfortunately...
From Daniel Lemire's Blog
Encoding binary in ASCII very fast
In software, we typically work with binary values. That is, we have arbitrary streams of bytes. To encode these arbitrary stream of bytes in standard formats like...
From Daniel Lemire's Blog
Science and Technology links (May 2nd 2020)
As we age, we tend to produce less of NAD+, an essential chemical compound for our bodies. We can restore youthful levels of NAD+ by using freely available supplements...
From Daniel Lemire's Blog
For case-insensitive string comparisons, avoid char-by-char functions
Sometimes wew need to compare strings in a case-insensitive manner. For example, you might want ‘abc’ and ‘ABC’ to be considered. It is a well-defined problem for...
From Daniel Lemire's Blog
Sampling efficiently from groups
Suppose that you have to sample a student at random in a school. However, you cannot go into a classroom and just pick a student. All you are allowed to do is to...
From Daniel Lemire's Blog
Science and Technology links (April 25th 2020)
People’s muscles tends to become weaker with age, a process called sarcopenia. It appears that eating more fruits and vegetables is associated with far lower risks...
From Daniel Lemire's Blog
Rounding integers to even, efficiently
When dividing a numerator n by a divisor d, most programming languages round “down”. It means that 1/2 is 0. Mathematicians will insist that 1/2 and claim thatContinue...
From Daniel Lemire's Blog
Science and Technology links (April 11th 2020)
Greenland sharks reach their sexual maturity when they are 150 years old and they live hundreds of years. Some living sharks today were born in the 16th century...
From Daniel Lemire's Blog
Multiplying backward for profit
Most programming languages have integer types with arithmetic operations like multiplications, additions and so forth. Our main processors support 64-bit integers...
From Daniel Lemire's Blog
Science and Technology links (April 4th 2020)
Antartica was once a rainforest. Google’s DeepMind built artificial intelligences that can defeat human beings at all of the standard Atari (arcade) games. The...
From Daniel Lemire's Blog
We released simdjson 0.3: the fastest JSON parser in the world is even better!
Last year (2019), we released the simjson library. It is a C++ library available under a liberal license (Apache) that can parse JSON documents very fast. How fast...
From Daniel Lemire's Blog
Science and Technology links (March 28th 2020)
In a laboratory, we know how to turn any of our cells into youthful stem cells using something called the Yamanaka. If you expose cells to such factors for a short...
From Daniel Lemire's Blog
Avoiding cache line overlap by replacing one 256-bit stores with two 128-bit stores
Memory is organized in cache lines, frequently blocks of 64 bytes. On Intel and AMD processors, you can store and load memory in blocks of various sizes, such as...
From Daniel Lemire's Blog
Number of atoms in the universe versus floating-point values
It is estimated that there are about 1080 atoms in the universe. The estimate for the total number of electrons is similar. It is a huge number and it far exceeds...
From Daniel Lemire's Blog