En.wikipedia.org

Given an array of size \(N\), return the element that appears more than \(\lfloor N/2 \rfloor\) times. Solve the problem in \(\mathcal{O}(N)\) time and \(\mathcal{O}(1)\) space.

Solving this in \(\mathcal{O}(N)\) time precludes sorting as that takes \(\mathcal{O}(N\ logN)\) time. Using \(\mathcal{O}(1)\) space precludes having a dictionary of frequencies. What is special about a frequency that is \(> \lfloor N/2 \rfloor\)? What kind of arithmetic would such a value survive?

In a sorted array, a number that appears \(> \lfloor N/2 \rfloor\) times is also the median. How can we compute the median of an unsorted array in \(\mathcal{O}(N)\) time and \(\mathcal{O}(1)\) space? Scratch that, the median is a more general problem as the frequency need not be \(> \lfloor N/2 \rfloor\).

implements a toy version of Python’s object system using dictionaries that contain references to properties, functions and other dictionaries. Consider two shapes, Square and Circle, with the methods perimeter, area, and density.

Objects

A function is an object, where the bytes in a function are instructions. For example:

def foo():
  print("in foo")

… creates an object in memory that contains instructions to print a string, and assigns that object to the variable foo.

MCP 101

There are 3 key participants in the MCP architecture:

• MCP Host: The AI application that manages one or more MCP clients, e.g., Claude Code, Copilot, etc.
• MCP Client: A component that maintains a connection to an MCP server and obtains context from an MCP server for the MCP host to use.
• MCP Server: A program that provides context to MCP clients.

Tower of Babylon

#religious-fiction

#divine-retribution-motif

Saga. Brian Vaughan; Fiona Staples. imagecomics.com . www.hoopladigital.com . en.wikipedia.org .

Themes (Mostly War)

Planet Landfall (Alana’s) and Wreath (its moon, Marko’s) have been in conflict as long as anyone can remember. Destroying either would send the other out of orbit, so they make peace at home, but outsource the combat to foreign lands. Most locals didn’t really think about the battles being waged in their names in distant lands. #societal-apathy

Babel, or the Necessity of Violence. An Arcane History of the Oxford Translators' Revolution. R. F. Kuang. en.wikipedia.org . Aug 23, 2022. ISBN: 9780063021426 . Accessed Jan 17, 2026.

On Language

Language was always the companion of the empire, and as such, together they begin, grow, and flourish. And later, together, they fall.

Parsing

The input is a list of all robots’ current positions \(p = (x, y)\) and velocities \(v = (dx, dy)\), one robot per line, e.g.,

p=3,6 v=4,-7
p=9,2 v=-1,-2

\(x\) represents the number of tiles away from the left wall, and similarly for \(y\) from the top wall (when viewed from above). The top-left corner of the space is \((0, 0)\). The velocity is given in tiles per second.

Of Self-Proclaimed Messiahs

• Recreational Programming with
• Hackers :
  • Ch 1: The Tech Model Railroad Club
  • Ch 2: The Hacker Ethic
  • Ch 3: Spacewar
  • Ch 4: Greenblatt and Gosper
  • Ch 5: The Midnight Computer Wiring Society
  • Ch 6: Winners and Losers
  • Ch 7: Life
  • The Last of the True Hackers
• Margaret Hamilton, the Engineer Who Took the Apollo to the Moon
• Rise of Worse Is Better
• The Inner Ring
• In the Beginning was the Command Line
• Mathematical Games - The fantastic combinations of John Conway’s new solitaire game ’life’
• Conway’s Game of Life - Wikipedia
• Interviewing Principles
• An Insider’s View of ‘Ciscogate’
• More Tales From ‘Ciscogate’
• What is Engineering?
• Any 5 stories from Folklore

1. CS 81N: Hackers and Heroes. Keith Winstein. web.stanford.edu . Accessed Dec 14, 2025.
2. Racket. racket-lang.org . Accessed Dec 14, 2025.
3. Hackers: Heroes of the Computer Revolution. Steven Levy. 1984. ISBN: 978-0-385-19195-1 .
4. Margaret Hamilton, the Engineer Who Took the Apollo to the Moon | by Verne | Medium. verne.medium.com . Accessed Dec 14, 2025.
5. Rise of Worse Is Better. Richard Gabriel. www.dreamsongs.com . Accessed Dec 14, 2025.
6. The Inner Ring. CS Lewis. www.lewissociety.org . Accessed Dec 14, 2025.
7. In the Beginning was the Command Line. Neal Stephenson. web.stanford.edu . Accessed Dec 14, 2025.
8. Mathematical Games - The fantastic combinations of John Conway's new solitaire game 'life'. Martin Gardner. web.archive.org . Accessed Jun 2, 2009.
9. Conway's Game of Life - Wikipedia. en.wikipedia.org . Accessed Dec 14, 2025.
10. Four Principles. www.columbia.edu . Accessed Dec 14, 2025.
11. Information Security News: An Insider's View of 'Ciscogate'. Jennifer Granick. seclists.org . Aug 31, 2005. Accessed Dec 14, 2025.
12. [ISN] More Tales From 'Ciscogate'. Jennifer Granick. attrition.org . Accessed Dec 14, 2025.
13. What is Engineering: A Graphic Novel of Tech and Philosophy - SparkFun Learn. Mel Chua. learn.sparkfun.com . Accessed Dec 14, 2025.
14. Folklore.org: The Original Macintosh. www.folklore.org . Accessed Dec 14, 2025.

Sample Use Cases

A collection of notes/impressions from titles where I didn’t find enough to necessitate a dedicated page. Usually short works of fiction.

Unknown Number

Unknown Number. Blue Neustifter. twitter.com . genderdysphoria.fyi . Jul 27, 2021. Accessed Sep 6, 2022.

tells the story of a person who has gender dysphoria. In an alternate universe, they never transitioned but went on to become an established physicist who could communicate across parallel universes.

Parsing

Each line represents a single equation, e.g., 292: 11 6 16 20.

Part One needs to make a decision based on each line independently. Parsing each line into a data structure and yielding that should suffice.

using System.Collections.Immutable;
using System.Text.RegularExpressions;

namespace AoC2024;

public partial class BridgeRepair
{
    public static IEnumerable<CalibrationEquation> Parse(string filePath)
    {
        using var inputReader = new StreamReader(filePath);

        string? line;
        while ((line = inputReader.ReadLine()) != null)
        {
            var numbers = InputLineRegex.Matches(line)
                .Select(match => long.Parse(match.Value));
            yield return new(numbers.First(), numbers.Skip(1).ToImmutableList());
        }
    }

    public readonly record struct CalibrationEquation(
        long Result, ImmutableList<long> Operands);

    private static Regex InputLineRegex = NumbersRegex();

    [GeneratedRegex(@"\d+")]
    static private partial Regex NumbersRegex();
}

Part One

Using only add and multiply, evaluated left-to-right (not according to math precedence rules), determine which equations could possibly be true. For example, \(292 = ((11 + 6) \times 16) + 20\). Of the equations that could possibly be true, what is the sum of their results?

Parsing

The notation X|Y means that if both page number X and page number Y are to be produced as part of an update, page number X must be printed at some point before page number Y.

The input contains page ordering rules (pairs of X|Y) and print queues (e.g., 75, 47, 61, 53, 29).

using System.Collections.Immutable;
using System.Text.RegularExpressions;

namespace AoC2024;

public partial class PrintQueue
{
    public readonly Dictionary<int, HashSet<int>> orderingRules = [];
    public readonly ImmutableList<ImmutableList<int>> printJobs = [];

    public PrintQueue(string filePath)
    {
        using StreamReader inputReader = new(filePath);
        string? line;

        while ((line = inputReader.ReadLine()) != null)
        {
            var match = OrderingRuleRegex().Match(line);
            if (match is null || !match.Success)
                break;
            
            var p1 = int.Parse(match.Groups["p1"].Value);
            var p2 = int.Parse(match.Groups["p2"].Value);

            var existed = orderingRules.TryGetValue(p1, out var p1Rules);
            p1Rules ??= [];
            p1Rules.Add(p2);

            if (!existed)
                orderingRules.Add(p1, p1Rules);
        }

        var printJobsBuilder = printJobs.ToBuilder();
        while ((line = inputReader.ReadLine()) != null)
        {
            printJobsBuilder.Add(
                line.Split(",").Select(int.Parse).ToImmutableList());
        }
        printJobs = printJobsBuilder.ToImmutable();
    }

    [GeneratedRegex(@"(?<p1>\d+)\|(?<p2>\d+)")]
    private static partial Regex OrderingRuleRegex();
}

Part One

Determine which updates are already in the correct order. What do you get if you add up the middle page number from those correctly-ordered updates?

The Dilemma

There are wide productivity variations between good programmers and poor ones. Sackman et. al. found 10:1 ratios. The data showed no correlation between experience and performance.

The major part of the cost of large teams is communication, and system debugging to correct the ill effects of miscommunication.

Android Calculator

Making a precise calculator is not trivial. While \(10^{100} + 1 - 10^{100} = 1\), iOS’s calculator gives back \(0\). explores how Android’s calculator gets this right courtesy of .

Real number representations are fundamentally imprecise because we can’t squeeze in infinitely many real numbers into a finite number of bits. Floating-point representations have a base \(\beta\) (assumed to be even) and a precision \(p\), e.g., if \(\beta = 10\) and \(p = 3\), then \(0.1\) is represented as \(1.00 \times 10^{-1}\). IEEE 754, a dominant floating point representation, requires \(\beta = 2, p = 24\) for single precision and \(p = 53\) for double precision. In IEEE 754, \(0.1\) cannot be represented exactly as \(1/10\) is not a factor of \(2\); it is approximately \(1.10011001100110011001101 \times 2^{-4}\).

tldraw.com’s Take on an LLM Canvas

In UX history, chat has tended to precede canvas. From running computers from the command prompt to using the screen as a canvas via a mouse. Mobile phones went from being keypad oriented into a canvas where the finger controls the touchscreen. Where are the canvases for LLMs?

Multi-modal models, e.g., GPT-4 and Gemini, can take image, video, and text inputs, and produce output.

#religious-fiction

#extraterrestrial-possession

​​The Recurrence. Every 90 years, 12 gods reincarnate on earth for 2 years. In 2014, the gods are living as pop icons. Some are high culture, e.g. Lucifer, and others are underground, e.g. The Morrígan.

The Department of Truth | Image Comics. James Tynion IV; Martin Simmonds. imagecomics.com . Accessed Feb 18, 2022.

Plot Points

[Lee Harvey Oswald] The more people believe in something, the more true that thing becomes. The more reality tips in the favor of that belief. What happened in Antartica was that a group of men managed to make enough people believe in the truth of a flat earth for it to manifest in reality… Retroactively, the earth would always have been flat. And the people would rightly rise up in fury having been lied to by everyone for decades. #tulpa

Plot Points

[Xavier] Wanda, put the world back now! [Wanda] No! [Xavier] Put it back! [Wanda] But my children! [Xavier] Never existed!

[Logan] Someone do the math for me… How many more of you does she have to kill before you snap out of it?

Bitter Root. David F. Walker; Chuck Brown; Sanford Greene. imagecomics.com . www.hoopladigital.com .

#extraterrestrial-possession

Snapshots

[Dr. Sylvester] I am not the devil. It was the devil that made me what I have become, and the devil I am here to destroy. Look around you, Enoch Sangerye. You’ve seen this before – cities and towns burned to the ground. It always starts with their hate and fear. And it always ends with our deaths. You saw the hell unleashed in the summer of 1919.

Invisible Kingdom. G. Willow Wilson; Christian Ward. www.darkhorse.com . www.hoopladigital.com . 2019. Accessed Dec 3, 2022.

A Flawed Religious Organization

[Vess] But what if… What if you found something here that seemed wrong? That seemed out of place? [Krikko] I would go straight to Mother Proxima and ask for guidance. That’s why she’s here. [Vess] And… If the something wrong had to do with Mother Proxima herself? [Krikko] Then I would question myself. Because doubting her would mean I had strayed from my vow of obedience.

Doom Patrol (1987-1995). Grant Morrison; Richard Case; John Nyberg. www.dcuniverseinfinite.com . www.hoopladigital.com . 1987. Accessed Dec 23, 2022.

Punchlines

Father McGarry has long since ceased to believe in miracles. Saturdays, he trudges out to the dump, looking for God among the debris. Saturdays are always the longest days and, in the winter, chilly. He asks for very little. Some trace, some evidence, some spoor of the divine. Some sign. It begins to rain fish. Mackerel. Herring. Sea bass. Pike. Sturgeon. Tench. Plaice. Salmon. From a clear sky. Trout. No cod.
FATHER McGARRY. Ha. [Crushed to death by a falling refrigerator]

Vision Vol. 1: Little Worse Than A Man. Tom King; Gabriel Hernandez Walta. www.marvel.com . www.hoopladigital.com . Jun 29, 2016. Accessed Feb 5, 2023.

Snapshots

Most of the Visions’ neighbors worked downtown, and they talked often about the traffic on 66 or Lee highway. On the weekends they tended to stay in Virginia, though they often lamented that they should go into the city. The museums are so nice, and the kids would have a great time. Very few of them were from the area originally. Most had moved to D.C. after college and worked for congress or the president. They made nothing, and they lived off of nothing. But that was unimportant. They were young, and they wanted to save the world. Eventually, they met someone and fell in love and had children. With bills to pay, they left their small government jobs; they became lobbyists and lawyers and managers. They moved out to the suburbs for the schools. They made the compromises that are necessary to raise a family.

Superman: Birthright. Mark Waid; Leinil Francis Yu; Gerry Alanguilan; Dave McCaig. www.dc.com . www.hoopladigital.com . 2003. Accessed Mar 24, 2023.

Snapshots

JOR-EL. For the thousand orbits, a shining planet circled a celestial font of heat and light. The people of that world grew tired of war so they achieved a united society. They feared the unknown… so they conquered it with the marvels of science. They yearned for heaven… so they created it beneath their very feet. For ten thousand orbits, a clump of dirt careened around a red dwarf star. And it accomplished miracles no one will ever remember.

Star Trek: Year Five. Brandon Easton; Jody Houser; Jim McCann; Collin Kelly; Jackson Lanzing. idwpublishing.com . www.hoopladigital.com . memory-beta.fandom.com . 2019.

Snapshots

SPOCK. They Lloyd Zeta hypergiant is the single most massive stellar object ever detected by Starfleet. And according to calculations by both the Vulcan Science Academy and Starfleet, within the next five minutes… it will explode, emitting a high-yield gamma ray burst that will effectively sterilize this entire sector. While this system is uninhabited, mass extinctions will occur on any habitable plants within a ten thousand light year range of the burst.

Snapshots

ARCA. Good morning, children. It is time to awaken. It is time to serve. Another day is here! A day to take joy in your work. Remember, the role of each settler is essential to the mission. Because there is only one way that we will reach Eden. And that is…
CHILDREN. …TOGETHER!

The Sandman Universe: Nightmare Country. James Tynion IV; Lisandro Estherren; Yanick Paquette; Andrea Sorrentino. www.dc.com . www.hoopladigital.com . sandman.fandom.com . 2022.

Snapshots

MR. ECSTASY. Dreams are a trap. They comfort and they coddle. They comfort and they coddle. They give false hope, and false understanding. They are little fictions that satisfy a man’s hunger for meaning, without providing anything he can hold in his hands. What matters is chasing the real. It’s what you can touch. What you can feel. Allow me to demonstrate.

The American Jesus Trilogy. Mark Millar; Peter Gross. imagecomics.com . www.hoopladigital.com . 2019. Accessed Jan 30, 2024.

Snapshots

It’s a coming of age story interrogating how a hero is formed, how a villain is created, and how similar the lives of the righteous and wretched can be, how fine the fault lines of good and evil are.

MyNBA is my favorite playing mode in NBA 2K. Starting out as the GM of the Seattle Supersonics in 1983, how well can I steer the franchise?

Playing all 82 games per season would need \(82 \text{ games/season} \times 41 \text{ seasons} \times 20 \text{ min/game} \approx 47 \text{ days}\) to catch up to today’s NBA and that’s not accounting for the playoffs. Simulating games is the way to go; might help improve my understanding of the game.

Version Control Systems track changes to a folder and its contents in a series of snapshots. Each snapshot encapsulates the entire state of files/folders within a top-level directory.

Git’s interface is a leaky abstraction. While the interface is at times ugly, its underlying design and ideas are beautiful. A bottom-up explanation of Git therefore makes more sense.

Stuck in Traffic

Blocked By Another Team

Understand and explain. Why is the work is important? What do you want from them and by when? Give them another chance to indicate feasibility and/or alternatives.

Make the work easier. Can you ask for a smaller subset of features? Can you help unblock their dependencies. Note that supporting your foray into their code base might cost them more in support and they might decline your offer.

Technical Analysis

Study past price movements and trading volume of trading to to predict when to buy/sell a stock. Based on the castle-in-the-air view of stock pricing.

Minimum Penalty for a Shop. leetcode.com . Accessed Jul 21, 2024.

Problem

You are given the customer visit log of a shop represented by a zero-indexed string customers consisting only of characters N and Y. If the \(i^{th}\) character is Y, it means that customers come at the \(i^{th}\) hour, whereas N indicates that no customers come at the \(i^{th}\) hour.

#meritocracy #inequality #socioeconomics

Our Lot in Life

Not recognizing your blessings feeds into the dark side of capitalism and meritocracy: success is a choice, and that those who haven’t achieved success are not unlucky, but unworthy.

Looking for parallels should be done cautiously. For example, the advantaging associated with race may be different from the one associated with heterosexism. It’s also hard to disentangle [dis]advantaging where social class, economic class, race, religion, sexuality, ethnic identity, and other factors interact.

Exercise 1: Have a regular savings program.

Start investing early because compound interest and time are you greatest resource.

Love

Dream: Sister – you know how I felt for Nada one. What I feel for her still. But she defied me. I gave her due earning, and she still spurned me, so… Death: So you sentenced her to hell.

Parable of the Sower. A Graphic Novel Adaptation (Original by Butler, 1993). Damian Duffy; John Jennings; Octavia E. Butler. www.abramsbooks.com . www.hoopladigital.com . 2020. ISBN: 978-1-4197-3133-4 .

Notable Plot Moments

“A pessimist if I’m not careful.” She did not just reject pessimism once and become a Pollyanna thereafter. It was an impulse that she had to quell over and and over. It was a dynamic and continuous act, a hard-nosed practice of staring down the worst of humanity’s evils and refusing to live in denial, all the while choosing to remember that humanity is also capable of great good.

Snow, Glass, Apples

Snow White is a vampire. She fed on her father (consensually?), the King, to the point of him being a shadow of a man. Her stepmother, the Queen, was only 18 when the King died. The Queen had witnessed Snow White’s vampirism, and so she had a servant kill her by carving out her heart and dump her in the forest.

#extraterrestrial-possession

The Last Days of Ptolemy Grey. Walter Mosley. en.wikipedia.org . www.apple.com . 2022-03-11. Accessed Feb 4, 2023.

Snapshots

[Ptolemy] Well, what I always tell Reggie he got to do? [Reggie] Uh, I got to take care of my kids. I got to go to the doctor if I run a fever. And… And, uh, I got to put in at least ten dollars in the bank every time I get paid.

Mental Attitude While Learning

Distinguish Mere Facts From Conclusions or Opinions

Discriminate between mere statements of facts, necessary conclusions which follow therefrom, and mere opinions which they seem to render reasonable. There’s no need to perform an experiment to verify that the atomic weight of oxygen is 16. That the sum of the angles of a plane triangle equals two right angles is not a mere fact, but an inevitable truth.

What Are Design Patterns?

Arriving at designs that are specific to the problem at hand but general enough to address future problems and requirements is hard. New designers tend to be overwhelmed by the options available. Expert designers do not solve every problem from first principles; they reuse design patterns.

Faster Human Trials

In 1986, AZT (AIDS treatment) showed 1/145 deaths compared to the placebo’s 16/137. 6,000 AIDS patients were offered AZT, helping it get to the public much faster.

Premise: Orr can have “effective” dreams that retroactively change reality for everyone else, except those who are aware of him dreaming. See for a refresher on the plot.

Notable Plot Points

Prodded by Haber to dream of the end of overpopulation, Orr dreamt of a plague that killed 6B people. But Orr tries to convince himself that the world that was was fiction in his head, so he didn’t really kill anyone.

Criticism/Defense Of Billionaire Philanthropy

Taxes will probably not go to the same causes, e.g. reforming the bail system, grassroot efforts for migrants, etc.

Foundations are more effective than governments as they do their due diligence, e.g. Bill Gates. Reforming the government is a long battle.

Stability, Testing and the Multi-Process Architecture

In a single-threaded browser, devs use asynchronous APIs - which may sometimes hold the browser up. Instead of multiple threads, Chromium chose multiple processes: isolation, independent crashes, better asymptotic memory management, identifying expensive sites, etc.

Journals

note that prediction services can still make accurate predictions using a fraction of the data collected from a user device. They propose Cloak, which suppresses non-pertinent features (i.e. those features which can consistently tolerate addition of noise without degrading utility) to the prediction task. Cloak has a provable degree of privacy, and unlike cryptographic techniques, does not degrade prediction latency. Using the training data, labels, a pre-trained model and a privacy-utility knob, they (1) find the pertinent features through perturbation training, and (2) learn utility-preserving constant values for suppressing the non-pertinent data. During the inference phase, they efficiently compute a sifted representation which is sent to the service provider.

Offensive Playmaking and Scoring

tracks the following play types: transition, isolation, pick & roll ball handler, pick & roll roll man, post up, spot up, handoff, cut, off screen and put-backs.

Intent

A one-to-many dependency between object so that when one object (subject) changes, all its dependents (observers) are notified and update automatically.

Main resource: .

What is Modular Arithmetic?

Where \(A\) and \(B\) are integers, we can write:

$$ \frac{A}{B} = Q \text{ remainder } R $$

Using the same \(A, B, Q, \text{ and } R\) as above, we have:

$$ A \text{ mod } B = R $$

\(A \text{ mod } B\) can be visualized as taking \(A\) steps on a clock that runs from \(0\) to \(B-1\). If the number is positive we step clockwise, if it’s negative we step counterclockwise.

Link Prediction

Given network-structured data, predict whether a link exists between two nodes.

Applications include: predicting drug-drug interactions (common in treating patients with complex/co-existing diseases) as they may cause changes in the drugs’ pharmacological activity .

Formal Software Design

Alloy is an open-source language and analyzer for software modeling. An Alloy model is a collection of constraints that describe a set of structures, e.g. all possible security configurations of a web application. Alloy’s tool, the Alloy Analyzer is a solver that takes the constraints of a model and finds structures that satisfy them.

Strange Loops

A Strange Loop occurs whenever, by moving upwards (or downwards) through the levels of some hierarchical system, we unexpectedly find ourselves right back where we started.

The 3-voice Canon Per Tonos from Musikalisches Opfer BWV 1079 exhibits a strange loop. Successive modulations make one expect to hopelessly far from the starting key, but after six modulations, the original key of C minor is restored!

Two Types of Thinking

Soldier Mindset

Reasoning is like defensive combat. Finding out you’re wrong means suffering a defeat. Seeks out evidence to fortify and defend your beliefs.

Directionally motivated reasoning. When we want something to be true, we ask, “Can I believe this?” When we don’t want something to be true, we ask, “Must I believe this?”

Scout Mindset

Reasoning is like mapmaking. Finding out you’re wrong means revising your map. Seeks out evidence that will make your map more accurate.

Why Even Read Papers?

While tutorials and docs help you write code right now, the academic papers can help you understand where programming came from and where it’s going. You also understand the paths that foundational academic research did not take. There’s a lot of things that are old that are new again, over and over and over. The idea of Stack Overflow is that someone else has had your problem before; the idea of academic papers is that someone else has thought about this problem before.

#code-hygiene

On Abstractions

If you find yourself adding more parameters and if-statements to an existing abstraction, is the abstraction still apt? Why not remove the old abstraction and re-extract a new [more apt] abstraction? Devs frequently succumb to the sunken cost fallacy thinking that there must have been a reason that the code was written in a certain way.

Clang, LLVM, GCC, and MSVC

LLVM is an umbrella project, with several sub-projects, e.g. LLVM Core and Clang. LLVM Core libraries provide an optimizer and code generator for different CPUs. Clang is an “LLVM native” C/C++/Objective-C compiler which aims for fast compilation, useful error and warning messages, and a platform for building source-level tools. The Clang Static Analyzer and clang-tidy are examples of such tools.

Imaginative literature primarily pleases rather than teaches. It is much easier to be pleased than taught, but much harder to know why one is pleased. Beauty is harder to analyze than truth.

On the fiction’s importance, phrases it nicely:

But we could not live in this [real] world if we were not able, from time to time, to get away from it. We do not mean that imaginative literature is always, or essentially, escapist. In the ordinary sense of that term, the idea is contemptible. If we must escape from reality, it should be to a deeper, or greater, reality.

...

Reaction Times are Overrated

Elite athletes do not display superior reaction times to those of average people; most hover at 200ms.

However, games are played at speeds where 200ms is too slow, e.g. 100-mph baseballs, 130-mph tennis serves, etc.

Superior Perception

Athletes outperformed novices when asked if there was a ball in a rapidly flashed slide. Some athletes could even tell the slide’s game!

Environmentalism

Over the last 70 years, less than 10% of plastic waste has been recycled - it’s uneconomical. Recycling shifts attention from the environmental impact of plastics and their overproduction to the consumer’s willingness to recycle. Reducing and reusing is a much better environmental strategy. #environmentalism

Betting (and Gambling)

Product Differentiation and Price Discrimination

Product differentiation seeks to distinguish a product from a competing product to make it more attractive to a specific target market. Price discrimination occurs when the same goods/services are sold at different prices from the same company.

The human genome has sequences of nucleotide base pairs that are repeated over and over again. At each locus of interest, a person has two sets of repeats inherited from each parent. Each possible difference at a locus is an allele. The combinations of the possible differences at multiple loci form a DNA profile that can be used to tie suspects to a crime scene.

The Accuracy of DNA Testing is Wanting

74/108 crime labs erroneously incriminated a suspect during a mock study. The reported match statistic for whether the match was coincidental varied over 100 trillion-fold.

Luxottica - Queen of the Seven Kingdoms

Luxottica owns and licenses Armani, Brooks Brothers, Burberry, Chanel, Coach, DKNY, Dolce & Gabbana, Michael Kors, Oakley, Oliver Peoples, Persol, Polo Ralph Lauren, Ray-Ban, Tiffany, Valentino, Vogue and Versace.

Italy’s Luxottica also runs EyeMed Vision Care, LensCrafters, Pearle Vision, Sears Optical, Sunglass Hut and Target Optical. It also merged with the world’s leading maker of prescription eyeglass lenses and contact lenses, to form EssilorLuxottica.

Political Ads

Cambridge Analytica (CA) paid people to take in-app survey; mined FB profile data including friends’ data; crafted tailored sensitive ads to sway-able voters. Elections are about emotions, not facts. Data science and social media can help us make sense of and manipulate the chaos.

Should Platforms Be Neutral?

Facebook banned praise, support and representation of white nationalism and separatism, because the two concepts cannot be meaningfully separated from white supremacy and organized hate groups. Furthermore, people that search for related terms will have “Life After Hate” suggested to them.

Short Selling

Say $A shares are selling at $100, but I think they’re overpriced. So I borrow 10 shares, pay my brokerage interest and post some collateral. I then sell the shares for $1,000.

Contact Tracing

Big Picture

Release APIs to enable apps to interoperate between Android and iOS devices. Bluetooth-based contact tracing baked into Android and iOS, such that no app is needed for broadcasting/listening. This ensures broad adoption, but will be on an opt-in basis.

Dependency Management

Golang introduced a new library referencing mode to overcome limitations of the old one. While the two library modes are supported by Golang, they are incompatible, e.g. dependency management (DM) issues, reference inconsistencies, build failures, etc. did an empirical study that resulted in HERO, an automated technique to detect DM issues and suggest fixes. Applied to 19k Golang projects, HERO detected 98.5% on a DM issue benchmark, and found 2,422 new DM issues in 2,356 Golang projects. They reported 280 issues, and almost all of the fixes have adopted HERO’s fixing suggestions.

State Surveillance

In the aftermath of the Capitol insurrection, FBI was contacting people whose cellphones pinged cell towers near the Capitol during the riots. #state-surveillance

1. Why People Are Irrational About Politics. Michael Huemer. Philosophy, Politics and Economics. 2015.

Salient features of political disagreements: widespread (many people disagree on many issues), strong conviction/confidence, and persistent (difficult to resolve).

Political Disputes Are Not Explained by Miscalculation or Ignorance

Miscalculation Theory: Political issues are difficult and partisans make mistakes in their reasoning.

WWW ‘21: The Web Conference 2021

REST: Relational Event-Driven Stock Trend Forecasting

REST, an event-driven stock trend forecasting framework, that overcomes two limitations of existing event-driven models. Models the stock context, and learns the effect of event information on the stocks under different contexts. Constructs a stock graph and designs a new propagation layer to propagate the effect of event information from related stocks. #stock-trend-forecasting #computational-finance

#graph-based-learning

Why Birds Can Fly Over Mount Everest

#education

Societal Preference for STEM Over the Liberal Arts

Not everyone can [wants to?] take the sciences, but they were pushed out of their passions into applicable degrees like Business and Communications.

The initially high economic return to applied STEM degrees declines by more than 50% in the first decade. People who major in LA don’t get first jobs that are as lucrative, but they do catch up.

Governments tend to claim a shortage of STEM workers (who are valued for innovation and national defense), and allocate funds for increasing the student pipeline. However, the fact that STEM wages have stagnated, and new grads struggle to find jobs casts doubt on the claim. Furthermore, the data is murky (e.g. who is classified as STEM, is a STEM degree a pre-requisite for a STEM job) that it can be massaged to support a specific policy.

Bloom Filters

Motivation

A Bloom filter for a set \(X: \{x_1, x_2, …, x_n\} \) from some universe \(\mathbb{U}\) allows one to test whether a given item \(x \in \mathbb{B}\) is an element of \(X\). Hash tables can already answer \(x \in X\) queries in \(O(1)\) expected time, and \(O(n)\) space.

#utilitarianism

As the Last I May Know. Shi Lian Huang. www.tor.com . Accessed Dec 4, 2021.

Memorable Points

Background: Sere missiles can wipe out a city completely. Nyma’s nation has been the only recipient of a seres strike. They’ve since acquired their own seres stockpile. They’re engaged in war with an state that lacks seres weapons.

Crime Drama

Ozark’s highlights are Ruth Langmore’s 90s’ hip hop playlist, Wendy Byrde’s sociopathic ambition, and Del Rio’s suave. The show follows the Byrde family that has to launder money for the Navarro Cartel. The writers use shortcuts as the show proceeds, and grant excessive plot armor for the Byrde family in subsequent seasons.

Debugging 101

printf Debugging and Logging

In printf debugging, one adds print statements and keeps iterating until enough information has been extracted.

Using logging has several advantages over printf debugging: varying logging destinations (e.g. standard output, files, sockets, remote servers, etc.); severity levels (e.g. INFO, DEBUG, WARN, ERROR, &c) that support filtering of output; color-coding for readability.

Money was a sore point in the Holmes household. Holmes’s grandparents had squandered away their share of the Fleischmann fortune. Richard Fuisz, a family friend, was a flashy successful businessman.

Fuisz was offended that Elizabeth never consulted him. Fuisz made his money patenting medical inventions that he anticipated other companies would someday want.

How to Be Wrong

found that experts were barely able to forecast better than random chance. However, a small subset of people (coined “superforecasters” ) were better. In a competition, they beat teams of top professors and CIA professional analysts. These superforecasters were not smarter than everyone else nor did they have more knowledge/experience, they were great at being wrong.

Change your mind a little at a time. Seeing the world in shades of grey is less stressful, as the experience of encountering evidence against one of your beliefs is not high stakes.

Argument from Consequences

If God does not exist, then everything is permitted.

Straw Man

The essence of this technique is to caricature a position to make it easier to attack.

My opponent is trying to convince you that we evolved from chimpanzees who were swinging from trees, a truly ludicrous claim.

Environmentalists care more for snail darters and spotted owls than they do for people.

Appeal to Fear

You should give me all your valuables before the police get here. They will end up putting them in the storeroom, and things tend to get lost in the storeroom.

The Law of the Few

From 1995 to 1996, the # of children born in Baltimore with syphillis increased 500%. CDC blamed it on cocaine and reduction in clinics.

In 100k+ Colorado Springs town, the gonorrhoea epidemic tipped because of the activities of 168 people living in 4 small neighbourhoods, frequenting the same 6 bars.

Gaëtan Dugas, an Air-Canada flight attendant, is [mis?]regarded as “Patient Zero” for AIDS in the US. It’s claimed he had \(\approx\) 2,500 sexual partners over North America, and linked to 40 of the earliest cases of AIDS in CA and NY.

Incomplete List of Information Privacy Properties

• Control/consent, e.g. Cambridge Analytica exfiltrating FB users’ data

• Anonymity, e.g. Snowden leaking NSA docs without revealing his identity

• Limits on data collection, e.g. laws restricting government surveillance

• Limits on data use, e.g. US Genetic Information Nondiscrimination Act of 2008

The Principle

Brandolini’s Bullshit Asymmetry Principle: The amount of energy needed to refute bullshit is an order of magnitude bigger than to produce it.

Jonathan Swift: Falsehood flies, and the Truth comes limping after it; so that when Men come to be undeceiv’d, it is too late; the Jest is over, and the Tale has had its Effect…

Introduction

The Tipping Point is the biography of how little things had big effects.

From 1992 to 1997, murder rates dropped 64.3% to 770 and total crimes fell by \(\approx\) 50% to 355,893.

Geometric progressions are non-intuitive, e.g. if given a large paper and asked to fold it 50x, the stack’s height will be \(\approx\) the distance to the sun.

A class is a user-defined type provided to represent a concept in the code of a program. Essentially, all language facilities beyond the fundamental types, operators, and statements exist to help define better class or to use them more conveniently.

Day 7 - Advent of Code 2021. Eric Wastl. adventofcode.com . Accessed Mar 5, 2022.

Part I Description

A giant whale has decided that your submarine is its next meal, and it’s much faster than you are. There’s nowhere to run!

Suddenly, a swarm of crabs (each in its own tiny submarine - it’s too deep for them otherwise) zooms in to rescue you! They seem to be preparing to blast a hole in the ocean floor; sensors indicate a massive underground cave system just beyond where they’re aiming!

Day 6 - Advent of Code 2021. Eric Wastl. adventofcode.com . Accessed Mar 2, 2022.

Part I Description

The sea floor is getting steeper. Maybe the sleigh keys got carried this way?

A massive school of glowing lanternfish swims past. They must spawn quickly to reach such large numbers - maybe exponentially quickly? You should model their growth to be sure.

This page contains remarks on Haskell that I encountered when working with source files that span multiple AoC 2021 problems.

and have Haskell solutions. It’ll be nice to compare how they solved the problems. I don’t want to end up perfecting the wrong approach!

Setting Up Haskell Env for AoC

To manage dependencies, Cabal and Stack are pretty popular. Stack incorporates the Cabal build system.

Problem Statement

You are given the following information, but you may prefer to do some research for yourself:

• 1 Jan 1900 was a Monday.
• Thirty days has September,
  April, June and November.
  All the rest have thirty-one,
  Saving February alone,
  Which has twenty-eight, rain or shine.
  And on leap years, twenty-nine.
• A leap year occurs on any year evenly divisible by 4, but not on a century unless it is divisible by 400.

How many Sundays fell on the first of the month during the twentieth century (1 Jan 1901 to 31 Dec 2000)?

\(X\) is a binomial random variable if it takes the values \(0, 1, 2, …, n\) and

$$ \mathbb{P}\{X = k\} = { n \choose k } \cdot p^k \cdot (1 - p)^{n-k} $$

Sanity Check: Do the probabilities sum to 1?

$$ \sum_{k=0}^{n} \mathbb{P}\{X = k\} = \sum_{k=0}^{n} { n \choose k } p^k (1 - p)^{n-k} = \left( p + (1 - p) \right)^n = 1 $$