Recent content on Dan Shearer
Automatic file versioning is a very handy tool for reducing user errors and confusion, but not many people know this because only one versioning filesystem has been implemented in production. The OpenVMS ↗ operating system and its versioned filesystem was reckoned to have ten million users or more ↗ in 2004 across half a million or so VMS clusters. I was one of those users, and I have wanted…
In responding to a recent security problem I had to consider the idea of intent in computer software, so I looked to see what Margaret Hamilton ↗ has to say. Hamilton proved her ideas spectacularly during the first Apollo moon landing in 1969. A hardware failure generated unexpected errors ↗ , but the software coped by running the highest-priority tasks despite the barrage of errors and prevented…
I looked for every health data system that shares features with my Medical Snapshot proposal , something I’ve been working on since 2007. Such programmes medically measure people over time, store what they find, and don’t necessarily tell the individuals what their own data says. This article is what I learned about 26 systems, spanning nine decades from the Tuskegee Syphilis Study…
R code generating the quadrant plots for the Medical Snapshot comparative review.
The Rule-based Epidemic Modelling (RBEM) Project was funded by the UK Medical Research Council project (grant X/011658/1) to make rule-based modelling methodology more accessible to the infectious disease modelling community. The rule-based approach is instead of writing differential equations, and there can be human as well as technical advantages to this. Our pre-print (draft) paper illustrates…
This is about an Observer-only Medical system, which can be immensely useful to society and governments, helping understand health and reducing suffering. There are many such systems (I know of at least 26) but they all have a common principle: individuals have their health monitored and are not told the results. So what’s in it for the individual who gives up the right to their own health…
The Active Heat Exchanger (AHE) research programme started as an engineering development project, and discovered first an engineering research question and then a health research question. The AHE is a retrofit ventilation device which solves the problem of there being no large-scale, long-term environmental epidemiology data for indoor air quality , despite most humans spending most their lives…
Not Before Time started with a question: can time be connected to information as reliably as GPS connects position to location? The mathematics to do this is decades old and already running in production systems. I soon discovered this question has been substantially answered, and the next question was a lot more subtle: how can time-linked information be rolled out to society for practical…
Anthropic publishes its constitution ↗ along with research about where the constitution works and where it does not. The current version is an ethical treatise addressing Claude discussing safety, ethics, Anthropic’s guidelines, and helpfulness, in that order when they conflict. Anthropic favours cultivating good values and judgment over strict rules. In 2026, Anthropic’s operational…
I am using my personal Perseverance engine as I help develop the code, and I’m watching carefully to see how useful it is for developing analysis, review and writing. Evidence so far is mixed, but improving fast. I feel in control as I do with any other work tool, which I certainly do not when using a typical error-prone AI text interface. One of the reasons I feel in control is because…
💡 Advised not to have a scan due to radiation risk? If you or your children are advised against having a medical scan due to radiation risks, you are probably hearing ‘radiophobia’. Health services often confuse protecting patients receiving radiation with protecting radiation workers who may be in these environments for decades. It will take a while for practices within health…
AI is slow, and Agentic AI ↗ is even slower. I develop an MCP server ↗ that generates PDF documents, and I work with the Agentic Perseverance Composition Engine daily. Tasks that take maybe 5 microseconds on an operating system (eg, does a file called Things-to-Do exist? ) can take a million times longer, between 2 and 5 seconds, because each operation requires multiple round trips to a remote LLM…
AI ethics and safety work mostly focuses on making individual models smarter and better-behaved via guidelines and persuasion, with not much hope ↗ this will succeed. You should especially not feel safe when an AI company reassures you about their guardrails ↗ . When you hear guardrails think of telling a dog “Don’t bite the furniture inside the house today”, because you can…
There are many problems with the AI billions of people use in 2026, discussed endlessly at all levels of society. From the end of 2025 I became interested in the particular problems of ethics and reliability, and why the approaches taken by all of the large AI companies are not good enough. Predictability, or ‘alignment’ as they call it, is just not something we can expect from this…
From time to time I am engaged to help organisations in the UK and in the EU make decisions about where their data is stored, how it is accessed, and how to keep things as stable as possible over the next few years. This was a dizzying mess until 2025, and in 2026 there are some big decisions coming. Organisations need as much certainty as they can get for making decisions which are expensive to…
While working with the Rule-based Epidemic Modelling group at the University of Southampton ↗ I began to consider the wider context, outside our core area of studying malaria. On the one hand, the techniques of epidemiology save lives at scale, but on the other, emerging diseases and newer health-related epidemics are accelerating. It seemed as if the field of epidemiology was really struggling,…
Patents and the MIT License Some of my software projects use MIT so I have studied this issue. Although in many respects the world has moved on from copyright wars to much higher-stakes legal shenanigans, the detail of licensing still matters. In my case: My LumoSQL project is based on probably the most-used software, SQLite, whose license states it is in the “Public Domain”. The…
I made a new website recently. My goals: Modern-looking Easy to maintain, minimal infrastructure Content lasts indefinitely even as web technologies come and go I decided on a static website ↗ , with content in Markdown ↗ and a modest amount of templating. I chose the Hugo ↗ static site generator with the PaperMod ↗ theme, plus a second theme ↗ for CV-type timelines. I used bundled system fonts…
My new website ↗ is nice enough, but it really needs work. I’m offering prizes! Small fixes for wording, grammar or links — my warmest thanks A page or more of such small fixes — I will buy you the (non-outrageous) beverage of your choice A substantial improvement or correction consisting of a page or more — a pizza from a mutually agreed place 10 non-trivial pull requests…
This file is a Code of Conduct first written in 2020 for the LumoSQL project. Here is Version 1.6 – Updated 9th February, 2026. Heavily adapted and compressed from the (very large indeed) version 3.1 of the Mozilla Participation Guidelines, and published by LumoSQL under the Creative Commons Attribution-ShareAlike 4.0 International license. Contents LumoSQL Code of Conduct This file exists because…
The detail of the GDPR and its implied computer science contain a solution for sharing secrets according to law. This continues to be true in 2026, as the Digital Omnibus Regulation ↗ takes shape. Executive Summary The GDPR sets up a conflict in trust between companies in particular circumstances, which can only be resolved by using the automation of a cryptographic audit trail with particular…
When Linux was a Struggling Challenger 💡 Key Point This is a 2026 restoration of my (Dan Shearer’s) 1998-2001 guide, preserved at archive.org ↗ . Links have been updated to point to the archives where possible. In 1999 I joined my first startup, Linuxcare in San Francisco. The Linuxcare story is a quintessential United States dot-com bubble narrative, featuring a famous venture capital…
This is the second time ↗ the Court of Justice has decided the same question. In brief, after 4 years, in 2020 the Court was completely satisfied that the United States violates the privacy of EU citizens when the personal data of EU citizens is visible to the US government, and that the US has no intention of changing its behaviour. Therefore, US companies are not permitted to hold the personal…
The Fossil ↗ source code management system is the most fully-featured alternative to Git, and has had twenty years of development and testing since 2006. After helping Fossil make some changes I now use Fossil for several projects. I also use Git extensively on various software forges (but not GitHub unless I must). Mercurial ↗ is actively maintained but has lost most of its mindshare since…
LumoSQL ↗ protects data on mobile phones using a new data storage technology which is highly compatible with most existing devices. With LumoSQL, the device owner has ultimate right to decide who can read or change their data… and this decision continues to be enforced even after it has been copied off the phone to (for example) a bank or insurance company for processing with their in-house…
I participated in many battles directly against Microsoft in the Ballmer era, 1998-2014. Every Samba feature release seemed to further anger Microsoft. Copyright and then especially patents were weaponised, as well as well-funded hit teams aimed at spreading confusion and intimidating their own (Microsoft’s!) customers. In the Nadella era from 2014-present, Microsoft and other tech giants…
This timeline covers the period when Microsoft decided free software and Samba in particular was an existential threat. Microsoft often buried competitors in expensive litigation, but turned out to be much more difficult to bury open source like Samba . This was the Ballmer era, named after the then-CEO, and the history of Samba’s triumphs feels highly relevant to 2026 where other giant…
In 2026, the Samba Project ↗ is nearly 30 years old and has conservatively a billion users. Samba started when I got upset at Microsoft for trying to monopolise all computer networking. I discovered some unmaintained but interesting open source software for sharing files and printers with workstation computers. And the rest is the official Samba history . Samba is implemented by talented software…
I have an interest in non-electronic computers as an educational tool. An horologer is someone who makes mechanical clocks and watches, and horologers definitely don’t believe in electronics. That’s why I published Shearer, D. (2007). "Communication: A Request for Collaboration." Horological Journal, 149(12), p. 471. , which sounds much fancier than the letter to the editor it was.…
How to manage BibLaTeX across time and cultures I wrote a paper in English using LaTeX ↗ on the topic of Epidemiology and One Health . Some essential references did not exist in English. That might sound simple — just list the originals, plus some translation/cross-referencing work to get the necessary information! It isn’t that simple. This howto is for LaTeX authors with references…
(written in 2008) How a young Australian discovered Open Source and a career. Eventually learning that a mixture of code, law and mathematics is a frontier for human rights battles. It isn’t often I come face to face with myself after a twenty-something year break, but I did yesterday. As a first year university student at the South Australian Institute of Technology ↗ in Adelaide I did…
Large Language Models are subject to the laws of physics in a bad way, because they use so much electricity and make so much heat. I was interested to learn about a Mr Landauer and his principle of thermodynamic reversibility, which suggests physics might also help, by greatly reducing the amount of power required by AI datacentres. That still leaves many, many AI problems including an economic…
Not-forking ↗ is a technical tool for software development. Not-forking assists with reproducibility. Here are some simple ways of explaining what Not-forking can do: Not-forking lets you integrate non-diffable codebases, a bit like patch/sed/diff/cp/mv rolled into one. Not-forking is a machine-readable file format and tool. It answers the question: What is the minimum difference between multiple…
Reversible execution creates computers that seem to run backwards, applying time shifting techniques with simulation/virtualisation to address software unreliability and complexity. I stand by my excited comments from way back in 2005: Reversibility is the biggest advance in debugging since source code debugging — Me, on the GDB developers list ↗ In 2026, reversibility still isn’t seen…
I have been lead implementer of the main security and privacy standards several times each. These can seem intimidating, but properly used they improve security overall, and can help a business run more smoothly. From a pragmatic, business point of view: These standards are about writing down the actual rules of your business relevant to security and privacy, and then writing down how you improve…
These exercises assume a CS graduate-level background and familiarity with the tools mentioned; they are for mentors to adapt for their students. I have either created or been subjected to all of them over the years, and I have mentored students through them on many occasions. The general theme here is that most of the systems and stacks that are taken for granted often don’t work very well,…
Random humans and computers Humans are terrible at randomness. If you ask people to write down a list of random numbers the result can usually be shown to not be random at all. Stage magicians and marketing experts exploit our inability to assess how random an event is. But computers, surely they should be random? It sure feels like it when your printer jams. But no, computers are often worse than…
Hello! I am Dan Shearer, dan@shearer.org . I live in Scotland and practice in Europe, the US and Oceania. Me You can verify and email me securely . The rest of this site has notes and results from my work in industry, academia and rights-related passions. I work between policy and governance on the one hand, and the technical implications of computing and medical science on the other, with…