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Conceptual model by Ciro Santilli 37 Updated 2025-07-16
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Slacktivism by Ciro Santilli 37 Updated 2025-07-16
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Philosophy by Ciro Santilli 37 Updated 2025-07-16
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Apostle not in the Twelve by Ciro Santilli 37 Updated 2025-07-16
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Free will by Ciro Santilli 37 Updated 2025-07-16
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Ciro Santilli does not believe in free will of course because he is an agnostic and he believes that brains are controlled by the laws of physics, see also: physics and the illusion of life.
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Tacoism by Ciro Santilli 37 Updated 2025-07-16
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Alan Watts by Ciro Santilli 37 Updated 2025-07-16
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While listening to endless hours of vaporwave while coding, Ciro Santilli spotted some amazing Buddhist-like voice samples, and eventually found that they were by Allan Watts.
Self-help? Maybe. Cult leader? Maybe. But at least it is one that Ciro buys into.
Is there a correlation between software engineers and Buddhism and liking the dude? Because this exists: wattsalan.github.io
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CIA 2010 covert communication websites / dnshistory.org by Ciro Santilli 37 Updated 2025-07-16
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dnshistory.org contains historical domain -> mappings.
We have not managed to extract much from this source, they don't have as much data on the range of interest.
But they do have some unique data at least, perhaps we should try them a bit more often, e.g. they were the only source we've seen so far that made the association: headlines2day.com -> 212.209.74.126 which places it in the more plausible globalbaseballnews.com IP range.
TODO can it do IP to domain? Or just domain to IP? Asked on their Discord: discord.com/channels/698151879166918727/968586102493552731/1124254204257632377. Their banner suggests that yes:
With our new look website you can now find other domains hosted on the same IP address, your website neighbours and more even quicker than before.
Owner replied, you can't:
At the moment you can only do this for current not historical records
This is a shame, reverse IP here could be quite valuable.
In principle, we could obtain this data from search engines, but Google doesn't track that entire website well, e.g. no hits for site:dnshistory.org "62.22.60.48" presumably due to heavy IP throttling.
Homepage dnshistory.org/ gives date starting in 2009:
Here at DNS History we have been crawling DNS records since 2009, our database currently contains over 1 billion domains and over 12 billion DNS records.
and it is true that they do have some hits from that useful era.
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CIA 2010 covert communication websites / Backlinks by Ciro Santilli 37 Updated 2025-08-08
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Announcements and updates by self:
Pings by self:
Reactions by others:
Notable reactions to the websites themselves:
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100 Greatest Discoveries by the Discovery Channel (2004-2005) by Ciro Santilli 37 Updated 2025-07-16
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Hosted by Bill Nye.
Physics topics:
biology topics:
Genetics:
Medicine:
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Fermat's last theorem by Ciro Santilli 37 Updated 2025-07-16
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A generalization of the Pythagorean triple infinity question.
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Spectrum (functional analysis) by Ciro Santilli 37 Updated 2025-07-16
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Skills / Grading scale stoles from a Goolge interview by Ciro Santilli 37 Updated 2025-07-16
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10You literally have written a book.
7 - 9Expert, go-to person on this technology.
5 - 6Solid daily working knowledge. Highly proficient.
3 - 4Comfortable working with this, have to check manual on some things.
1 - 2Have worked with it previously but either not much, or rusty.
I copied this grading scale mechanism from a failed Google interview ;-)
One problem with it is that I am always very hesitant to put a 5 on anything, who can not look at the documentation?
It is also hard to scope things right. Who can claim to be a C++ or Linux kernel expert, even if you wrote a book about it, since those are such humongous topics?
As a result, I haven't updated this in a while, and things may be out of date.
If your project does something that interests me, I can what it takes to contribute. Tell me what I must know, how long I have to learn it, and I'll call you back when I've mastered it.
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Where to store images by Ciro Santilli 37 Updated 2025-07-16
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Since images are large, they bring the following challenges:
  • keeping images in the main Git repository with text content makes the repository huge and slow to clone, and should not be done
  • storing and serving images could cost us, which we want to avoid
To solve those problems, the following alternatives appear to be stable enough and should be used decreasing preference:
The following do have direct links:
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Try to fix your own bike before taking it to the shop by Ciro Santilli 37 Updated 2025-07-16
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Sometimes you get annoyed to death with your bike not breaking or changing gears perfectly as you would like, and the people at the bike shop never do the job well enough.
The problem with bike shops is that the employees are already swamped with work, and they don't get paid any extra for doing more work.
As a result, paradoxically, they are often happier, and respect you more if you are trying to get them to help you to fix your own bike!
Also, for the same reason, they don't have the time to go for a quick test ride after a fix to ensure that the bug was actually fixed.
So they ignore things that would obviously be huge ridability benefits (although they might not be obvious to newbie customers), for which customers would gladly pay more money for.
But you start to learn how to do stuff yourself and it feel amazing when you finally get there (after infinite trial and error).
Ciro dreams of a bike shop that actually calls you for the appointment and then teaches you how to fix the thing.
So the best strategy is to have a backup bicycle, and when your main one breaks, you just try to to the fix yourself. That means:
  • identifying the broken piece
  • watching YouTube videos of how to do the job
  • buying a replacement and any missing tools on Amazon
  • giving it a shot
Then, if you fail to do the fix, that is OK, just take it to the bike shop, with the piece you've bought, and ask them to do it for you. At least this way you did not waste a golden opportunity to learn!
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Maxima and minima by Ciro Santilli 37 Updated 2025-07-16
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Given a function :
we want to find the points of the domain of where the value of is smaller (for minima, or larger for maxima) than all other points in some neighbourhood of .
In the case of Functionals, this problem is treated under the theory of the calculus of variations.
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Lebesgue integral of is complete but Riemann isn't by Ciro Santilli 37 Updated 2025-07-16
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And then this is why quantum mechanics basically lives in : not being complete makes no sense physically, it would mean that you can get closer and closer to states that don't exist!
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OurBigBook.com / Blogs by Ciro Santilli 37 Updated 2025-07-16
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Where blog is taken in a wide sense, including e.g. Medium, WordPress, Facebook, Twitter, etc., etc.
The main shortcoming of blogs is the lack of topic convergence across blogs. Each blog is a moderated castle. So who is the best user for a given topic, or the best content for a given tag, across the entire website?
The only reasonable free material we have for advanced subjects nowadays are university lecture notes.
While some of those are awesome, when writing a large content, no one can keep quality high across all sections, there will always be knowledge that you don't have which is enlightening. And Googlers are more often than not interested only in specific sections of your content.
Our website aims to make smaller subjects vertically curated across horizontal single author tutorials.
MIT calculus course             UCLA calculus course

* Calculus                <---> * Calculus
  * Limit                 <--->   * Limit
    * Limit of a function
    * Limit of a series   <--->     * Limit of a series
  * Derivative            <--->   * Derivative
                                    * L'Hôpital's rule
  * Integral              <--->   * Integral
Some more links:
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Iterative pre-order by Ciro Santilli 37 Updated 2025-07-16
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This is the easiest one to do iteratively:
  • pop and visit
  • push right to stack
  • push left to stack
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Metric (mathematics) by Ciro Santilli 37 Updated 2025-07-16
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A metric is a function that give the distance, i.e. a real number, between any two elements of a space.
A metric may be induced from a norm as shown at: Section "Metric induced by a norm".
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Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
Video 1.
Intro to OurBigBook
. Source.
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
    Video 2.
    OurBigBook Web topics demo
    . Source.
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 2.
    You can publish local OurBigBook lightweight markup files to either OurBigBook.com or as a static website
    .
    Figure 3.
    Visual Studio Code extension installation
    .
    Figure 4.
    Visual Studio Code extension tree navigation
    .
    Figure 5.
    Web editor
    . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
    Video 4.
    OurBigBook Visual Studio Code extension editing and navigation demo
    . Source.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact
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