# 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

• **August 2, 2024.** Added a clarification explaining that we work in framework of classical logic. And improved the explanation for the “implication paradox” due to Gowers (note 4 in §2).

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.

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

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.