Apollonius' problem involves finding a circle that is tangent to three given circles in a plane. This classic problem in geometry has several special cases depending on the configurations of the given circles. Here are some notable special cases: 1. **Tangency to Three Disjoint Circles**: If the three circles do not overlap and are positioned such that they are completely separated, there can be up to eight distinct circles that are tangent to all three given circles.
Not really dedicated to open source course material, nor to free courses...
The "Open" in its name only made sense in the 60's, when it was founded, nowadays, there isn't much about this institution that is very different compared to traditional Oxbridge. "Cheap more online university" would be a more adequate name for it.
A system that would truly live up to the name "Open" in the year 2020 is the one described at the ideal university by Ciro Santilli.
Wikipedia even says that the initial focus was on broadcasting learning material on television and radio, so what happened to that now that we have an even more powerful on-demand tool called Internet!
They even created their own MOOC website, FutureLearn. But www.freecodecamp.org/news/massive-open-online-courses-started-out-completely-free-but-where-are-they-now-1dd1020f59/ mentions:OMG. God why.
The course content is still free to access, but it’s only available for the duration of the course, and for two weeks after it ends.
A few open sources at: www.open.edu/openlearn/free-courses. The 5-hour course on particle physics says it all. Stated as of 2023 at www.open.ac.uk/about/open-educational-resources/openlearn/free-learning:
www.youtube.com/watch?v=Pj0rbafFBak What's an Open University Degree Like? by Luke Cutforth (2021) mentions that it is more autodidactic/online, and it encourages part time learning.
youtu.be/rsWwffX-u0A?t=99 Open University - How does it work? by Matt Greg Vlogs (2017) shows that they do have their own custom institutional material. And it is not open???? Please. youtu.be/rsWwffX-u0A?t=222 mentions that there is no entry exam, and you can change your courses at any time, that is good at least.
Israel apparently also created their own version in the 70's inspired by the British one: Open University of Israel. Same story it seems.
Nice, nice place. Natural sciences only, no bullshit.
CIA 2010 covert communication websites Common Crawl by 
Ciro Santilli 37 Updated 2025-07-01 +Created 1970-01-01
Ciro Santilli 37 Updated 2025-07-01 +Created 1970-01-01So far, no new domains have been found with Common Crawl, nor have any existing known domains been found to be present in Common Crawl. Our working theory is that Common Crawl never reached the domains How did Alexa find the domains?
Let's try and do something with Common Crawl.
Unfortunately there's no IP data apparently: github.com/commoncrawl/cc-index-table/issues/30, so let's focus on the URLs.
Using their Common Crawl Athena method: commoncrawl.org/2018/03/index-to-warc-files-and-urls-in-columnar-format/
Sample first output line:So
# 2
url_surtkey org,whwheelers)/robots.txt
url https://whwheelers.org/robots.txt
url_host_name whwheelers.org
url_host_tld org
url_host_2nd_last_part whwheelers
url_host_3rd_last_part
url_host_4th_last_part
url_host_5th_last_part
url_host_registry_suffix org
url_host_registered_domain whwheelers.org
url_host_private_suffix org
url_host_private_domain whwheelers.org
url_host_name_reversed
url_protocol https
url_port
url_path /robots.txt
url_query
fetch_time 2021-06-22 16:36:50.000
fetch_status 301
fetch_redirect https://www.whwheelers.org/robots.txt
content_digest 3I42H3S6NNFQ2MSVX7XZKYAYSCX5QBYJ
content_mime_type text/html
content_mime_detected text/html
content_charset
content_languages
content_truncated
warc_filename crawl-data/CC-MAIN-2021-25/segments/1623488519183.85/robotstxt/CC-MAIN-20210622155328-20210622185328-00312.warc.gz
warc_record_offset 1854030
warc_record_length 639
warc_segment 1623488519183.85
crawl CC-MAIN-2021-25
subset robotstxturl_host_3rd_last_part might be a winner for CGI comms fingerprinting!Naive one for one index:have no results... data scanned: 5.73 GB
select * from "ccindex"."ccindex" where url_host_registered_domain = 'conquermstoday.com' limit 100;Let's see if they have any of the domain hits. Let's also restrict by date to try and reduce the data scanned:Humm, data scanned: 60.59 GB and no hits... weird.
select * from "ccindex"."ccindex" where
fetch_time < TIMESTAMP '2014-01-01 00:00:00' AND
url_host_registered_domain IN (
'activegaminginfo.com',
'altworldnews.com',
...
'topbillingsite.com',
'worldwildlifeadventure.com'
)Sanity check:has a bunch of hits of course. Data scanned: 212.88 MB,
select * from "ccindex"."ccindex" WHERE
crawl = 'CC-MAIN-2013-20' AND
subset = 'warc' AND
url_host_registered_domain IN (
'google.com',
'amazon.com'
)WHERE crawl and subset are a must! Should have read the article first.Let's widen a bit more:Still nothing found... they don't seem to have any of the URLs of interest?
select * from "ccindex"."ccindex" WHERE
crawl IN (
'CC-MAIN-2013-20',
'CC-MAIN-2013-48',
'CC-MAIN-2014-10'
) AND
subset = 'warc' AND
url_host_registered_domain IN (
'activegaminginfo.com',
'altworldnews.com',
...
'worldnewsandent.com',
'worldwildlifeadventure.com'
)While in Brazil, Ciro Santilli used to walk through the outskirts of a small favela to get to university every day, the Favela de São Remo.
See the street view for: R. Catumbi - Vila Butantã Vila Butantã, São Paulo - State of São Paulo, Brazil, e.g. with this link.
To the right, dudes selling drugs on the entry of a small corridor street, presumably to which they could easily escape to in case of need.
The cops could have identified the dealers with binoculars if they actually wanted to!!!
The drug sellers did keep the peace in their business area, and Ciro never got robbed, and would come back from university parties on foot late through the favela.
But Ciro's friends did say that things got much worse after Ciro left, for example a flash kidnapping was reported in 2015.
Wikipedia says that this favela started in the 60s and 70s as settlements of the builders of the University, and that many of the people there still work for the University.
This is consistent with the terribly old buildings Ciro saw when he was at university. They even had the building skills to build their own homes.
The state just has to either legalize those people, or give them houses somewhere else nearby. A world class University is the most important thing a poor country can have, and its image cannot be jeopardized like that.
The existence of that favela, right next to one of the most important universities in Latin America, puts Brazil's surreal social inequality into perspective. Especially considering that before extremely heavy university entry quotas were added, basically all students of the university (or at least of the courses that lead to high paying jobs) had attended private schools, and therefore were not of the poorer classes (see passage about 10 out 500 passage from Section "Free gifted education").
The janitors of the apartment block Ciro lived all lived in the favela. Yes, in poor countries lives are worth nothing, and some poorer people work by watching the entrance of buildings of less poor people 24/7 to guard it from other even more desperate poor people who might want to rob the not so poor inhabitants. They also do janitor jobs like cleaning common areas in parallel.
They were incredibly nice hard-working people, and Ciro spoke often with them. If only given the opportunity, those people could be amazing engineers or scientists obviously. Ciro was also glad to be their friends, and sat down with them quite a few times for several minutes after coming back from University parties, partly because he felt bad about them having to work at that time, but also partly because he just liked them. And they were always up to date on who had come back with a girl to the apartment or not. Ciro imagines that if it had been him, it would have been a perfect bragging opportunity ;)
They had "nothing" but were still happy. This is true wisdom, and a good reminder that all our non-transhumanist technical goals are nothing.
We must destroy social inequality.
Susanne Teschl is a notable academic primarily recognized for her work in the field of mathematics, particularly in the area of differential equations and dynamical systems. She is often associated with research and teaching in applied mathematics, and may be involved in various academic collaborations and publications.
The 2019 World Jigsaw Puzzle Championship was an international competition held in November 2019 in Belgium. It brought together puzzle enthusiasts from around the world to compete in assembling jigsaw puzzles under timed conditions. The event featured competitors working on the same puzzle, showcasing both speed and skill in a challenging and engaging environment. Participants came from various countries, and the championship is part of a larger tradition of competitive jigsaw puzzling that has been growing in popularity.
The 2018 Google walkouts were a series of protests held by Google employees in November 2018. The walkouts were organized in response to the company's handling of sexual harassment allegations and the treatment of employees who reported such misconduct. The protests stemmed from a New York Times report that detailed how Google had reportedly paid millions of dollars in severance packages to executives accused of sexual harassment, effectively allowing them to leave the company without facing any significant consequences.
The 2013 Bulgarian nuclear power referendum was a national plebiscite held on January 27, 2013, to gauge public opinion on the future of nuclear energy in Bulgaria, specifically regarding the construction of the Belene Nuclear Power Plant. The referendum was called in response to significant public debate and political contention surrounding the project, which had been effectively halted due to various concerns, including environmental issues, financial implications, and safety considerations after the Fukushima nuclear disaster in 2011.
The 2011 Tōhoku earthquake and tsunami was a devastating natural disaster that struck the northeastern coast of Japan on March 11, 2011. It was one of the most powerful earthquakes ever recorded, with a magnitude of 9.0. The epicenter was located off the Pacific coast of Tōhoku, about 70 kilometers (43 miles) east of the city of Sendai.
The 2006 Argentine nuclear reactivation plan refers to a policy initiative articulated by the Argentine government aimed at revitalizing and expanding the country's nuclear energy program. Following a period of stagnation after the economic crises of the late 1990s and early 2000s, Argentina sought to re-establish itself as a significant player in the nuclear energy sector.
In category theory, the concepts of full and faithful functors relate to the ways in which a functor preserves certain structures between categories.
The number 1 is a natural number that follows 0 and precedes 2. It is the first positive integer and has several important properties in mathematics: 1. **Identity Element**: In multiplication, 1 is the multiplicative identity, meaning that any number multiplied by 1 remains unchanged (e.g., \( n \times 1 = n \)).
1Lib1Ref, short for "One Librarian, One Reference," is a global campaign aimed at improving the quality of content on Wikipedia and other Wikimedia projects by encouraging librarians and library professionals to add at least one reliable reference to Wikipedia articles that lack proper citations. The initiative was launched to help address the issue of citation gaps in Wikipedia content and to engage librarians in enhancing the reliability and credibility of information available on the platform.
The 19th century was a significant period for Finnish mathematics, as Finland was establishing its identity and academic institutions following its independence from Swedish rule in 1809. During this time, several Finnish mathematicians made contributions to different fields, including pure mathematics, applied mathematics, and mathematical education.
In retrospect, doing electrical engineering (and likey the other engineering degrees) felt like taking a trip to the 60s in the United States, due to both the subject matter, and how old the concrete buildings were!
This does not need to be a bad thing. It is in that era (and earlier) that much of the exciting foundations of the field were set, and there is great value in there is value in tutorials written by early pioneers of the field. Not that they were amazing at excting history lessons as they should be. But the course outline suggested that intent.
But that point of view must also be accompanied by the excitement of the great ongoing advances of technology (and impact they had in the past). And on that, they failed.
Pinned article: ourbigbook/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!
Intro to OurBigBook
. Source. We have two killer features:
- 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-calculusArticles 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/derivativeVideo 2. OurBigBook Web topics demo. Source. - 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.
- to OurBigBook.com to get awesome multi-user features like topics and likes
- as HTML files to a static website, which you can host yourself for free on many external providers like GitHub Pages, and remain in full control
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 5. . 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. 
- Infinitely deep tables of contents:
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