Ciro Santilli's hardware Phillips D400 cordless phone Updated 2025-07-16
Reflections of the Moon on Erquan Updated 2025-07-16
Relationship between the quotient group and direct products Updated 2025-07-16
Although quotients look a bit real number division, there are some important differences with the "group analog of multiplication" of direct product of groups.
If a group is isomorphic to the direct product of groups, we can take a quotient of the product to retrieve one of the groups, which is somewhat analogous to division: math.stackexchange.com/questions/723707/how-is-the-quotient-group-related-to-the-direct-product-group
The "converse" is not always true however: a group does not need to be isomorphic to the product of one of its normal subgroups and the associated quotient group. The wiki page provides an example:
Given G and a normal subgroup N, then G is a group extension of G/N by N. One could ask whether this extension is trivial or split; in other words, one could ask whether G is a direct product or semidirect product of N and G/N. This is a special case of the extension problem. An example where the extension is not split is as follows: Let , and which is isomorphic to Z2. Then G/N is also isomorphic to Z2. But Z2 has only the trivial automorphism, so the only semi-direct product of N and G/N is the direct product. Since Z4 is different from Z2 × Z2, we conclude that G is not a semi-direct product of N and G/N.
This is also semi mentioned at: math.stackexchange.com/questions/1596500/when-is-a-group-isomorphic-to-the-product-of-normal-subgroup-and-quotient-group
I think this might be equivalent to why the group extension problem is hard. If this relation were true, then taking the direct product would be the only way to make larger groups from normal subgroups/quotients. But it's not.
Ciro Santilli's hardware Timberland Larchmont Chukka Updated 2025-07-16
Bought 2021-11, light brown, size EUR 44.5, 190$, waterproof: www.timberland.co.uk/shop/en/tbl-uk/larchmont-chukka-for-men-in-brown-a12es210
Ciro Santilli's hardware Virgin Media 256 Mps nominal Updated 2025-07-16
Maxwell's equations require special relativity Updated 2025-07-16
The following aspects of Maxwell's equations make no sense without special relativity:
- the Lorentz force would be different observers have different speeds, see e.g.: charged particle moving at the same speed of electrons thought experiment
- Maxwell's equations imply that the speed of light is the same for all inertial reference frames
When charged particle though experiment are seen from the point of view of special relativity, it becomes clear that magnetism is just a direct side effect of charges being viewed in special relativity. One is philosophically reminded of how spin is the consequence of quantum mechanics + special relativity.
Meal deal Updated 2025-07-16
x.com/Birdyword/status/1777591446612193667Singaporean taxi drivers are the cutest.
A while ago a Singaporean taxi driver asked me what a UK hawker centre lunch might cost. I explained that there aren't any. He asked what office workers ate, and I explained the concept of Meal deals. And he looked at me with such a powerful combination of pity and revulsion.
Measure theory Updated 2025-07-16
Main motivation: Lebesgue integral.
The Bright Side Of Mathematics 2019 playlist: www.youtube.com/watch?v=xZ69KEg7ccU&list=PLBh2i93oe2qvMVqAzsX1Kuv6-4fjazZ8j
Mechanics problem Updated 2025-07-16
Mediocre Amateur Updated 2025-07-16
About 50k subscribers on 2021, which feels way too little for the video quality and quantity.
Ciro Santilli believes that this channel will go very far, certainly achieving 1M subscribers in they keep it for one or two more years. Update: it didn't, as of 2024, shame.
They are Utah-based, and they do many many amazing weekend trips. They mostly drive from home to some trailhead, and then climb up and down it the entire day.
No technical rock climbing, only bouldering, but they still manage to reach many amazing places, and there is a level of danger in many of their ascents.
Medium (website) Updated 2025-07-16
While this has some of the metrics features that Ciro Santilli wants to implement for OurBigBook.com, it limits the number of articles your readeres can read.
Melody of Longshuo Updated 2025-07-16
Ciro Santilli's knowledge hoarding Updated 2025-07-16
His uncle, which Ciro rassembles in many ways, was like that. But he collected physical objects such as wines and stamps. Or even worse, objects that were meant to be collected such Panini soccer sticker albums! This Ciro looks down on.
With computers, knowledge takes no physical space and can be immediately shared with the hole world, and there is great beauty to that, as you can just keep collecting forever without filling up your house.
But of course, physical or not, all attachments futile.
Like other types collecting, once Ciro decides that "he must know everything about a given subject", he will keep coming back to that subject over and over. Not in a systematic way of course, since Ciro is a lazy bastard, but he will keep coming back for a very long time, and eventually become an expert at it.
This compulsive hoarding, together with Ciro Santilli's bad old event memory, are the fundamental reasons for OurBigBook.com.
Ciro Santilli's love advice Updated 2025-07-16
In the field of Love and Friendship, Ciro is a big believer in the merciless application of tit for tat. Never desire someone's love if you give and what comes back is not proportional. Cut your attempts to reach out immediately in such cases.
Never tell a woman you like her before she is in your bed.
If someone likes you and you don't like them as much, make that clear to them. Don't put this off, be it for compassion, curiosity, loneliness, or narcissism.
youtu.be/Sb0VHGnhX4M?t=174 from Video "Charles Bukowski Scandanavian TV interviews":
The way to get a woman is not to have money, not to look nice, not to have a nice personality. The way to get a woman, is to always be available, night or day. Any time you phone, you're there, or you're at the bar. They know that you are available at all times. It is very, very important to a woman.
See also: Section "Ciro Santilli's wife".
Ciro Santilli's natural languages skills Updated 2025-07-16
- English: Cambridge CPE grade B in 2004. Proficient, with minor defects in collocation/pronunciation. Learned from formal courses and from living in the UK for a few months when he was 10.
- French: TCF grade C2 in 2011. Proficient, with a bit more defects than English. Studied and lived in France.
- Brazilian Portuguese: Native speaker
- Chinese: see github.com/cirosantilli/china-dictatorship/tree/df0852b22e585785d734ec69719eddf63f9676a5#do-you-speak-chinese
Memento mori Updated 2025-07-16
Memory semantics Updated 2025-07-16
These are the rules which specify what different concurrent read/write memory accesses from different threads/processes can or cannot see.
Notable such set of rules include:
- C++ memory model. These are also reflected on the semantics of memory of the corresponding instruction set architecture
- SQL transaction isolation level
High temperature superconductor superconducting magnet Updated 2025-07-16
History Updated 2025-07-16
Messaging software that force you to have a mobile phone Updated 2025-07-16
Chat programs that don't have a proper web-only operation and force you to have a mobile phone, e.g. WhatsApp.
Heck, even Signal, which is supposed to be super secure and good for your privacy, forces you to disclose your freaking cell phone to all contacts! lifehacker.com/how-to-use-signal-without-revealing-your-private-phone-1818996580
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