Posts on stau.space

Eq

sona@stau.space (Sona Tau Estrada Rivera) — Tue, 21 Jul 2026 14:11:58 -0400

First, I’d like to start with a quick sentence a friend said a really long time ago while we were taking Calculus I:

A set is just its cardinality.

At first, my reaction was to dismiss that as nonsense. I mean, look at these sets: $\{1\}$, $\{2\}$. They look very different to me, but their cardinality is the same. You mean to tell me that I can uniquely identify sets by their cardinality? I’ll cut the sarcasm now; yes you can do that identification and it’s actually not that crazy.

I Love Patina

sona@stau.space (Sona Tau Estrada Rivera) — Sun, 19 Jul 2026 18:27:59 -0400

This blog post will be slightly different than the usual Mathematics/CompSci focused posting.

When I used to study architecture, because I didn’t own a computer that had Windows installed on it, I would do many of the drawings required for the courses by hand. There I learned the absolute value there is in using tools which were made specifically for a single task. For example, I started out using drawing pencils (the ones that come in different hardness) to do the drawings. You’ll notice eventually that although the hardness is very important for drawing, the thickness with which the lines get made is equally if not more important. This meant that using regular wooden drawing pencils wouldn’t cut it, they would get blunt and thicken too fast. This is where mechanical drawing pencils came in. To this day, mechanical drawing pencils are my go-to when writing things down because of their versatility and resilience. Something else I’ve noticed about owning a single one of these pencils for the past 8 years is: this pencil might be plastic in some places and metal in others, but the used look of it looks very nice.

The best Algebraic Structure

sona@stau.space (Sona Tau Estrada Rivera) — Tue, 16 Jun 2026 11:48:48 -0400

An algebraic structure is a set with some functions associated to it that meet some axioms. Semi-groups, fields, loops, and magmas are all examples of algebraic structures. I won’t assume that the reader has dealt with any of these structures but I will assume that you know about set cardinality and the fact that these structures were originally created, mostly, in an abstract way in order to model different things. The best example for this, from a programming perspective, is that of the semigroup. If you want to parallelize a procedure in your program, a way to do this would be to demonstrate it forms a semigroup. If so, parallelizing it is super easy, since a semigroup’s operation is associative. I won’t go into too much detail on this since this is not the point of this post.

Language Semiring

sona@stau.space (Sona Tau Estrada Rivera) — Sun, 31 May 2026 20:28:46 -0400

I actually wrote this blog post a couple months ago but only decided to shape it up for posting today: june 18th.

In my computation theory class, after defining a regular expression, we also defined operations $\cdot$ and $\cup$. These operations would take a set of words in a regular language and construct yet another set of words. Interestingly, there were some special sets that make this look like a ring:

The empty set $\emptyset$ which has the following properties:
- It is an identity element for the $\cup$ operation: $\emptyset \cup A = A \cup \emptyset = A$.
- It is an annihilator element for the $\cdot$ operation: $\emptyset \cdot A = A \cdot \emptyset = \emptyset$.
The set with one element $\{\epsilon\}$ which is a language that only identifies the empty string has the following properties:
- It is an identity element for the $\cdot$ operation: $\{ \epsilon \} \cdot A = A \cdot \{ \epsilon \} = A$.

This makes it almost a ring with:

The Explorer's Trial

sona@stau.space (Sona Tau Estrada Rivera) — Sat, 07 Mar 2026 08:24:15 -0400

I really like trying out new software. Between me and my friends, I’m the designated weirdo who’s always trying out strange things on my devices. This gets me stares from others, but I don’t mind:

Can’t you just use something normal? — Ran D. Ompersson

This is normal for me. — Me

Well, maybe I could use something more normal? But time has proven that there are actually a lot of really cool things people have made out there. You’ll see later what I mean about this. Many times a lot better and a lot buggier than the widely established software projects, but still really cool. Some of them have been long forgotten, dead. Some of them have been reborn, whether that is knowingly or unknowingly of the original project escapes me, but I’m certain that the motivation for doing so is out of wanting the same solution the original project sought to accomplish.

The Eight Plain Text Questions

sona@stau.space (Sona Tau Estrada Rivera) — Thu, 05 Mar 2026 10:10:57 -0400

Based off Ellane W’s based off Scott Nesbit’s Eight questions for Donald Brown.

When did you start using plain text?

High school, around 2016.

Why did you start using plain text?

I had seen a couple videos at the time about Linux, and about a week later I had been given a laptop. Like many experts in their field, I am acutely aware of all the ways in which the systems I work with can run optimally and how easily they can also break. Many software developers know and strive towards having resilient systems, built in the most elegant way possible. I used to take notes by hand in notebooks, and computers seemed very interesting to me back then. Because of this, I had a series of requirements which my writing system had to meet:

2026 New Year's Resolution

sona@stau.space (Sona Tau Estrada Rivera) — Sat, 17 Jan 2026 16:45:07 -0400

January

Deadlines long overdue, the nadir of my grades, no personal projects in the past year, a stale mind floating on the river of time, and a general feeling of distrust emanating from those around me; all of them: indicators that I had simply stopped trying.

I have also realized that in order to solve my problems, I needed to stop and think about them before acting:

Frieren: Beyond Journey's End

sona@stau.space (Sona Tau Estrada Rivera) — Fri, 26 Dec 2025 00:00:00 -0400

Studio / Year: MADHOUSE (2023)
Date Watched: 2025年12月26日

Needless to say,

HERE BE SPOILERS

Visual & Formal Language

This was animated by MADHOUSE, the framing and composition seem very standard for animes of this time period. Lots of scenic introductory shots about the world using classic framing guidelines like “the rule of thirds” and “putting the horizon at the top or bottom”.

That’s not to say that the composition wasn’t great though. For example, take a look at the following shot:

The Phoenician Scheme Critique

sona@stau.space (Sona Tau Estrada Rivera) — Sun, 21 Dec 2025 00:00:00 -0400

The Phoenician Scheme

Director / Year: Wes Anderson (2025)
Date Watched: 2025-12-20

Visual / Formal Language

As a Wes Anderson movie. The framing was absolutely stunning. Every shot had some sort of symmetry happening in it. As if someone had animated a painting. The camera movement was basically nonexistent for the entire film. Except during the end when there was a fight scene and the camera started following the struggling faces of the characters. Other than that, there were fast movements between shots every now and then. The editing was mildly fast, and very abrupt. This makes sense since most shots were taken from a static perspective. There isn’t much movement to be done, and if the movement was absolutely necessary, then a quick cut was done to the thing that needed focus and back to the main event. The lighting and contrast was very soft. Many hot temperatured colors and pastel palettes were used for the rooms and in the outfits. The general color grading of the movie was slightly yellowish and cooled down for the climax of the movie. This adds to the feeling of the movie looking like a painting.

Trivial toki pona Substitutions

sona@stau.space (Sona Tau Estrada Rivera) — Sun, 16 Nov 2025 17:23:50 -0400

toki open

There is a family of programming languages that are called “Trivial Brainf*ck Substitutions” (TBFS for short). They basically take the 8 characters used in Brainf*ck and represent them using other strings of characters. This is (somewhat) the same idea behind sitelen pona and sitelen kuwi. I would even guess that it’s the same idea behind sitelen sitelen, but I don’t know enough yet about sitelen sitelen to make that conclusion.

Nasin Toki

sona@stau.space (Sona Tau Estrada Rivera) — Sat, 04 Oct 2025 16:29:43 -0400

toki a

This is my nasin for writing toki pona. My nasin includes things meant for better typesetting, improved readability of text, and preserving the generally artistic nature of toki pona whether that is in sitelen pona or sitelen Lasina.

ala la ........ > Related things should go together.
wan la ........ Use of "la", "ni" and indenting.
tu la ......... Vertical alignment.
tu wan la ..... Names in toki pona.
tu wan.wan la . Being respectful and beauty in names.
tu tu la ...... Use of multiple "pi" in a single sentence.

ala la

Most of the readability that I talk about boils down to:

¡Feliz Cumpleaños Izánder!

sona@stau.space (Sona Tau Estrada Rivera) — Mon, 07 Jul 2025 18:56:46 -0400

Primer Riddle

I have no door, but I open and close.

nasin toki

sona@stau.space (Sona Tau Estrada Rivera) — Thu, 12 Jun 2025 20:27:45 -0400

toki a

This is my nasin for writing toki-pona. My nasin includes things meant for better typesetting, improved readability of text, and preserving the generally artistic nature of toki-pona whether that is in sitelen-pona or sitilen Lasina.

ala la

Most of the readability that I talk about boils down to “put stuff that’s similar together”. When dealing with multiple subjects, several headnouns or verbs, your text might get cluttered and you might end up with a huge paragraph of text. This can be readable, but it doesn’t have to be this way. Specially in sitelen-pona where horizontal and vertical spaces and symmetry are significant to the piece of text you are writing about.

Mathematics in toki pona

sona@stau.space (Sona Tau Estrada Rivera) — Wed, 11 Jun 2025 00:00:00 -0400

FAQ

Frequently asked questions about toki pi (nasin nanpa).

toki pi kulupu pini

sona@stau.space (Sona Tau Estrada Rivera) — Mon, 20 Jan 2025 07:50:59 -0400

The Cult of Done is a manifesto written by Bre Pettis with Kio Stark in August of 2016.

English manifesto

A Monad Is Not A Burrito

sona@stau.space (Sona Tau Estrada Rivera) — Sat, 21 Dec 2024 10:34:47 -0400

Repeat after me:

A monad is NOT a burrito.

A monad is NOT a taco.

A monad is NOT a wrapper.

Algorithms

sona@stau.space (Sona Tau Estrada Rivera) — Sun, 08 Dec 2024 20:18:33 -0400

So it was a fine summer morning. Our research team was about to start our project “Counting Arithmetical Structures on Cycles with a Doubled Edge”. From the description of the project it is immediately obvious that this kind of counting can be done by brute force, and me being the only computer scientist in my group of mathematicians I start coding up a couple algorithms for this.

Translations

sona@stau.space (Sona Tau Estrada Rivera) — Sun, 08 Dec 2024 19:20:28 -0400

Here are several excerpts from miscellaneous texts that I have translated into toki pona.

AOC day 1

sona@stau.space (Sona Tau Estrada Rivera) — Thu, 05 Dec 2024 13:55:24 -0400

wan wan.
zz pana pi (toki tawa lipu) li nasin lipu tu e wan.
zz pana pi (toki tawa lipu) li suli.
zz poka li sin pana ala li nanpa sewi e luka.
zz ale li sin pana.

 ⍉ pana
⟨ ⟨ 4 3 5 3 9 3 ⟩ ⟨ 3 4 2 1 3 3 ⟩ ⟩
 ∧˘⍉ pana
⟨ ⟨ 3 3 3 4 5 9 ⟩ ⟨ 1 2 3 3 3 4 ⟩ ⟩
 |-˝∧˘⍉ pana
⟨ 2 1 0 0 1 5 ⟩
 +´|-˝∧˘⍉ pana
9

AOC day 2

sona@stau.space (Sona Tau Estrada Rivera) — Mon, 02 Dec 2024 00:00:00 -0400

Mathematics in toki pona

sona@stau.space (Sona Tau Estrada Rivera) — Mon, 02 Dec 2024 00:00:00 -0400

nasin nanpa lon toki-pona

The language toki pona (toki-pona) lacks a lot of common mathematical definitions. Although this is on purpose, I do enjoy talking about mathematics. In a language where kindness and compassion is so prevalent I see no reason why to avoid talking about something I feel so passionate about. Then, here is my documentation for how to speak about common mathematical terms.

Zig CTFP

sona@stau.space (Sona Tau Estrada Rivera) — Wed, 07 Aug 2024 11:38:20 -0400

Let this blog post be living proof that Zig is in fact also a functional programming language.

We Lost the ICPC Regionals

sona@stau.space (Sona Tau Estrada Rivera) — Sat, 21 Oct 2023 22:00:00 -0400

Posts on stau.space

Eq

I Love Patina

The best Algebraic Structure

Language Semiring

The Explorer's Trial

The Eight Plain Text Questions

When did you start using plain text?

Why did you start using plain text?

2026 New Year's Resolution

January

Frieren: Beyond Journey's End

Visual & Formal Language

The Phoenician Scheme Critique

The Phoenician Scheme

Visual / Formal Language

Trivial toki pona Substitutions

toki open

Nasin Toki

toki a

Table of contents

ala la

¡Feliz Cumpleaños Izánder!

Primer Riddle

nasin toki

toki a

ala la

Mathematics in toki pona

FAQ

toki pi kulupu pini

A Monad Is Not A Burrito

Algorithms

Translations

AOC day 1

AOC day 2

Mathematics in toki pona

Zig CTFP

We Lost the ICPC Regionals