What's new?

Material Implication – June 22, 2024.→ [preprint] ←
A brief note explaining why the logical connective “implication” is defined the way it is. #implication #material-implication #logical-connective #induction #proof-by-contradiction

The Algebra Of Two’s Complements – May 14, 2024.→ [preprint] ←
Explaining the mathematics behind the standard way of representing negative numbers in binary. #binary-representation #twos-complements #modular-arithmetic
• May 26, 2024. Corrected typos and improved the explanation of when (and when not) does modular addition coincide with regular integer addition.

A revolução que falta – 25 de Abril de 2024. 🇵🇹
Cinquenta anos depois de Revolução dos Cravos, como ficou conhecida a mudança de regime operada a 25 de Abril de 1974, deixo aqui uma pequena reflexão, não tanto sobre o que foi conseguido—que é sobejamente conhecido, quer pelos apoiantes de Abril, quer pelos seus detractores—mas sobre aquilo que ficou a faltar. Algo que continua a causar muita confusão, mesmo entre as mais férreas hostes da revolução. #portugal #revolução #cravos #25abril

Enumerate: continuing from previous one – April 18, 2024.
How to have the bullet number continue from a previous enumeration. #latex #enumerate #bullet #number

Exponentials and logarithms – April 10, 2024.→ [preprint] ←
A narrative-style introduction to exponentials and logarithms… #math #reals #exponentiation

Exponentiation rules in $\mathbb{R}$ – March 22, 2024.[preprint]
This is something one usually learns in a piece-wise fashion, because it is information that is usually scattered among all sorts of different books (analysis, algebra, etc.). Well, here I round it all up in one place. #math #reals #exponentiation

Backup on LUKS-encrypted external HDD – March 8, 2022.[Script] [Config]
One of my strategies to prevent important (electronic-form) information from becoming too ephemeral… #backups #rsync #luks #usb #drive
• March 21, 2024. Script can now be used with a user-specified config file $ sh /path/to/backup_script.sh -f /path/to/custom/config/file.sh. I also added the ability to exclude certain files or folders from being backed up; cf. the new config template.

The revenge of rsync – March 19, 2024.
This is a repost of a text first published on June 2013, in my previous blog, erroneousthoughts.org (now decommissioned). It illustrates how just one tiny character, can make a world of difference… #rsync #source-folder #forward-slash

The dangers of abstraction – March 19, 2024.
This is a repost of a text first published on June 2013, in my previous blog, erroneousthoughts.org (now decommissioned). It offers a good illustration of what can lurk hidden under a software layer of abstraction… #rsync #sshfs #ssh

LaTeX: Restate theorems, etc. – June 26, 2023.
For when your mathematical creations need an alter ego… #latex #theorems #restate
• Update, December 10, 2023. Added a clarification about the need to actually repeat the content of the theorem or whatever, when restating it…

TeX-7 – November 20, 2023.[Source code]
This is my toned-down fork from Elias Toivanen’s TeX-9 Vim plugin for writing LaTeX documents. #vim #plugin #snippets
• Update, November 21, 2023. The plugin’s full manual is now displayed here. Within Vim, hitting :help vim-tex-seven will only list the available maps, visual mode motions, etc., together with brief descriptions of each—and direct the user to the current page for further information.

Backup on LUKS-encrypted external HDD – March 8, 2022.[Script] [Config]
One of my strategies to prevent important (electronic-form) information from becoming too ephemeral… #backups #rsync #luks #usb #drive
• Update, August 31, 2023. The script now outputs messages to inform the user when the LUKS volume has been successfully mounted/unmounted. Moreover, two new options: -m mounts the LUKS volume, and nothing else; and -u unmounts the LUKS volume, and nothing else. Also, the configuration variables have been placed in a separate file, to ease setting them up.