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
Science and Technology links (July 16 2023)
Most people think that they are more intelligent than average. Lack of vitamin C may damage the arteries. Make sure you have enough! A difficult problem in software...
From Daniel Lemire's Blog
Recognizing string prefixes with SIMD instructions
Suppose that I give you a long list of string tokens (e.g., “A”, “A6”, “AAAA”, “AFSDB”, “APL”, “CAA”, “CDS”, “CDNSKEY”, “CERT”, “CH”, “CNAME”, “CS”, “CSYNC”, “DHC...
From Daniel Lemire's Blog
Stealth, not secrecy
The strategy for winning is simple: do good work and tell the world about it. In that order! This implies some level of stealth as you are doing the good work.Continue...
From Daniel Lemire's Blog
Packing a string of digits into an integer quickly
Suppose that I give you a short string of digits, containing possibly spaces or other characters (e.g., "20141103 012910"). We would like to pack the digits into...
From Daniel Lemire's Blog
Having fun with string literal suffixes in C++
The C++11 standard introduced used-defined string suffixes. It also added regular expressions to the C++ language as a standard feature. I wanted to have fun and...
From Daniel Lemire's Blog
Parsing time stamps faster with SIMD instructions
In software, it is common to represent time as a time-stamp string. It is usually specified by a time format string. Some standards use the format %Y%m%d%H%M%SContinue...
From Daniel Lemire's Blog
Dynamic bit shuffle using AVX-512
Suppose that you want to reorder, arbitrarily, the bits in a 64-bit word. This question was raised on Twitter by @experquisite. Formally, you might want to provide...
From Daniel Lemire's Blog
Science and Technology links (June 25 2023)
Women in highly religious relationships report the highest levels of relationship quality. US politics is largely divided into two parties (Republicans and Democrats)...
From Daniel Lemire's Blog
Science and Technology links (June 11 2023)
Similar species can have vastly different lifespan. Researchers have been looking for the limiting factors that explain these differences. As we age, our genesContinue...
From Daniel Lemire's Blog
Parsing IP addresses crazily fast
Most of us are familiar with IP addresses: they are strings of the form “ddd.ddd.ddd.ddd” where ddd is a decimal number of up to three digits in the range 0 toContinue...
From Daniel Lemire's Blog
Science and Technogy links (June 3 2023)
There are fewer serial killers these days. Some suggests it is due to better forensic techniques: we catch the killers faster and more efficiently. Between theContinue...
From Daniel Lemire's Blog
Peak credentialism
How much is a degree from a prestigious university worth? The answer is a bit difficult to answer because there are many cofounding factors: people from the connected...
From Daniel Lemire's Blog
Expected performance of a Bloom filter
A hash function is a function that maps a value (such as a string) to an integer value. Typically, we want random-looking values. A Bloom filter is a standard data...
From Daniel Lemire's Blog
The absurd cost of finalizers in Go
The Go programming language makes it easy to call C code. Suppose you have the following C functions: char* allocate() { return (char*)malloc(100); } void free_allocated...
From Daniel Lemire's Blog
Computing the UTF-8 size of a Latin 1 string quickly (ARM NEON edition)
While most of our software relies on Unicode strings, we often still encounter legacy encodings such as Latin 1. Before we convert Latin 1 strings to Unicode (e...
From Daniel Lemire's Blog
ARM instructions do “less work”?
Modern processors can execute several instructions per cycle. Because processors cannot easily run faster (in terms of clock speed), vendors try to get their processors...
From Daniel Lemire's Blog
Science and Technology links (May 6 2023)
Artificial intelligence (ChatGPT) can provide better answers to patients than physicians. Eating chocolate might affect your brain and cognitive functions. It may...
From Daniel Lemire's Blog
Graviton 3, Apple M2 and Qualcomm 8cx 3rd gen: a URL parsing benchmark
Whenever you enter a URL into a system, it must be parsed and validated. It is a surprisingly challenging task: it may require hundreds of nanoseconds and possibly...
From Daniel Lemire's Blog
Under Linux, libSegFault and addr2line are underrated
Many modern programming languages like Java produce useful error messages when they fail. Some indicate where in the program (e.g., down to the line of source code)...
From Daniel Lemire's Blog