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
Why we make up jobs out of thin air
“We prefer to invent new jobs rather than trying harder and inventing a new system that wouldn’t require everybody to have a job.” (Philippe Beaudoin) In the XXIst...
From Daniel Lemire's Blog
Facts about global warming that you should keep for yourself
I don’t get invited to parties very often. That is, in part, because I cultivate aggressively critical thinking. My wife will testify that I am doubter, an annoying...
From Daniel Lemire's Blog
Bytes or octets?
Quick: what is the definition of a byte (as in two kilobytes)? If you said it is a unit of 8 bits, you failed. Correct answer (according to IEEE 1541): A byte is...
From Daniel Lemire's Blog
Which is fastest: read, fread, ifstream or mmap?
If you program in C/C++, you have many options to read files: The standard C library offers a low-level read function. It is as simple as it gets. The standard...
From Daniel Lemire's Blog
Do not waste time with STL vectors
I spend a lot of time with the C++ Standard Template Library. It is available on diverse platforms, it is fast and it is (relatively) easy to learn. It has been...
From Daniel Lemire's Blog
On the quality of academic software
Software is eating the world. Despite a poor year, Facebook has a market capitalization of $65 billion. This little company with barely 2000 developers is worth...
From Daniel Lemire's Blog
Data alignment for speed: myth or reality?
Compilers align data structures so that if you read an object using 4 bytes, its memory address is divisible by 4. There are two reasons for data alignment: Some...
From Daniel Lemire's Blog
Creating incentives for better science
Popper argued that science should be falsifiable. To determine truth, we simply try to disprove an hypothesis until we are exhausted. It is a nice theory, but actual...
From Daniel Lemire's Blog
Fast bitmap decoding
An old programming trick is to represent sets of integers as bitmaps. For example, the sequence of integers 1, 4, 6 becomes the number 0b1010010 in binary (or 82...
From Daniel Lemire's Blog
Summer reading recommendations
What came after by Sam Winston is an intriguing scifi novel. It describes a near-future dystopia where a handful of large corporations have taken over the USA....
From Daniel Lemire's Blog
Punk money: how you can print your own currency
We all want and need money. However, for many services, paying actual dollars is inefficient. The transaction costs are too high. So we need a system whereas perfect...
From Daniel Lemire's Blog
Computer scientists need to learn about significant digits
I probably spend too much time reviewing research papers. It makes me cranky. Nevertheless, one thing that has become absolutely clear to me is that computer scientists...
From Daniel Lemire's Blog
Let us abolish page limits in scientific publications
As scientists, we are often subjected to strict page limits. These limits made sense when articles were printed on expensive paper. They are now obsolete. But we...
From Daniel Lemire's Blog
How to manipulate the masses by language alone
George Orwell with novel 1984 popularized the idea that by changing the language, you could change the minds. It is easy to forget that we are routinely victims...
From Daniel Lemire's Blog
Bit packing is fast, but integer logarithm is slow
In How fast is bit packing?, we saw how to store non-negative integers smaller than 2N using N bits per integer by a technique called bit packing. A careful C++...
From Daniel Lemire's Blog
It is what you do, not what you own
Over 20 years ago, back when I was in high school, I went on a sailboat trip. I was so impressed that I decided to own a sailboat one day. I realized that a sailboat...
From Daniel Lemire's Blog
Publicly available large data sets for database research
Most database research papers use synthetic data sets. That is, they use random-number generators to create their data on the fly. A popular generator is dbgen...
From Daniel Lemire's Blog
Do we need copyright?
The concept of property is a social construction. Animals, such as cats, can own a piece of food, or a territory, but only as long as they are able to personally...
From Daniel Lemire's Blog
From counting citations to measuring usage (help needed!)
We sometimes measure the caliber of a researcher by how many research papers he wrote. This is silly. While there is some correlation between quantity and quality...
From Daniel Lemire's Blog