Hive mind Updated 2025-07-16
Rich people who create charitable prizes are often crooked Updated 2025-07-16
A friend of mine who's a rich man - he invented some kind of simple digital switch - tells me about these people who contribute money to make prizes or give lectures: "You always look at them carefully to find out what crookery they're trying to absolve their conscience of."
Rickrolling Updated 2025-07-16
Riemann integral Updated 2025-07-16
The easy and less generic integral. The harder one is the Lebesgue integral.
Computer science course of the University of Cambridge Updated 2025-07-16
The courses are highly open, almost everything is given publicly except solutions, many of which are given to teachers only. Well done!
Past exam papers index: www.cl.cam.ac.uk/teaching/exams/pastpapers/
www.cl.cam.ac.uk/teaching/2223/
- www.cl.cam.ac.uk/teaching/2223/part1a.html year 1
- Michaelmas term
- www.cl.cam.ac.uk/teaching/2223/Databases/
- past exams:
- questions: public www.cl.cam.ac.uk/teaching/exams/pastpapers/t-Databases.html
- solutions: paywalled
- slides: public e.g. www.cl.cam.ac.uk/teaching/2223/Databases/djg-materials/databases_2223_1to4-B.pdf
- problem sheets:
- questions: public e.g. www.cl.cam.ac.uk/teaching/2223/Databases/djg-materials/supervision-1.html
- solutions: not available
- past exams:
- www.cl.cam.ac.uk/teaching/2223/Databases/
- Lent term
- Discrete mathematics
- problem sheets:
- question: public e.g. www.cl.cam.ac.uk/teaching/2223/DiscMath/solutions/DiscMaths1_Sols.pdf
- solutions: public e.g. www.cl.cam.ac.uk/teaching/2223/DiscMath/solutions/DiscMaths1_Sols.pdf
- problem sheets:
- ALgorithms 1
- lecture notes: www.cl.cam.ac.uk/teaching/2223/Algorithm1/2022-2023-stajano-algs1-handout.pdf
- problem sheet:
- questions: www.cl.cam.ac.uk/teaching/2223/Algorithm1/2022-2023-stajano-algs1-exercises.pdf
- solutions: not available
- www.cl.cam.ac.uk/teaching/2223/Algorithm1/
- Discrete mathematics
- Michaelmas term
Connect two computers directly without a router with an Ethernet cable Updated 2025-07-16
For IP-level communication, askubuntu.com/questions/22835/how-to-network-two-ubuntu-computers-using-ethernet-without-a-router/116680#116680 just worked between P51 and P14s both on Ubuntu 23.10 connected with a regular Cat 5e cable.
On both machines, first we found the Ethernet cable interface name with the which outputs on the P41s:so the interface was
ip CLI tool:ip a1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
2: enp1s0f0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP group default qlen 1000
link/ether fc:5c:ee:24:fb:b4 brd ff:ff:ff:ff:ff:ff
3: wlp2s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
link/ether 04:7b:cb:cc:1b:10 brd ff:ff:ff:ff:ff:ff
inet 192.168.1.123/24 brd 192.168.1.255 scope global dynamic noprefixroute wlp2s0
valid_lft 61284sec preferred_lft 61284sec
inet6 fe80::3597:15d8:74ff:e112/64 scope link noprefixroute
valid_lft forever preferred_lft foreverenp1s0f0, because wlp is wireless and lo is localhost.So on the P14s we assign an IP of 10.0.0.10 to the P51:
sudo ip address add 10.0.0.10/24 dev enp1s0f0Then on the P51 analogously, giving IP of 10.0.0.20 to the P14s:
sudo ip address add 10.0.0.20/24 dev enp0s31f6And after that, P14s can:and P51 can:
ping 10.0.0.10ping 10.0.0.20 Quantum Field Theory lecture notes by David Tong (2007) Updated 2025-07-16
Number of pages circa 2021: 155.
It should also be noted that those notes are still being updated circa 2020 much after original publication. But without Git to track the LaTeX, it is hard to be sure how much. We'll get there one day, one day.
Some quotes self describing the work:
- Perhaps for this reason Ciro Santilli was not able to get as much as he'd out of those notes either. This is not to say that the notes are bad, just not what Ciro needed, much like P&S:
In this course we will not discuss path integral methods, and focus instead on canonical quantization.
A follow up course in the University of Cambridge seems to be the "Advanced QFT course" (AQFT, Quantum field theory II) by David Skinner: www.damtp.cam.ac.uk/user/dbs26/AQFT.html
Riesz-Fischer theorem Updated 2025-07-16
A measurable function defined on a closed interval is square integrable (and therefore in ) if and only if Fourier series converges in norm the function:
Ring (mathematics) Updated 2025-07-16
A Ring can be seen as a generalization of a field where:
- multiplication is not necessarily commutative. If this is satisfied, we can call it a commutative ring.
- multiplication may not have inverse elements. If this is satisfied, we can call it a division ring.
The simplest example of a ring which is not a full fledged field and with commutative multiplication are the integers. Notably, no inverses exist except for the identity itself and -1. E.g. the inverse of 2 would be 1/2 which is not in the set. More specifically, the integers are a commutative ring.
The simplest non-commutative, non-division is is the set of all 2x2 matrices of real numbers:Note that is not a ring because you can by addition reach the zero matrix.
- we know that 2x2 matrix multiplication is non-commutative in general
- some 2x2 matrices have a multiplicative inverse, but others don't
RNA-Seq Updated 2025-07-16
Porn image detection Updated 2025-07-16
Peter Todd Updated 2025-07-16
Robert O'Callahan Updated 2025-07-16
He quit Mozilla in 2016 to try and commercialize an
rr extension called Pernosco.But as of 2022, he advertised himself as part of "Google Research", so maybe that went under, sample source: archive.ph/o9622. TODO when did he start? There's apparently an unrelated homonym: www.linkedin.com/in/rob-ocallahan/
He's apparently very religious, and very New Zelandish, twitter.com/rocallahan auto-describes:Terry A. Davis and D. Richard Hipp come to mind. One is tempted to speculate a correlation even, the proportion amongst systems programmers feels so much higher than in other areas of programming! Maybe it is because you have to be a God to do it in the first place.
Christian. Repatriate Kiwi.
Robert O'Callahan interview by Toby Ho (2022)
Source. Roberto Rossellini Updated 2025-07-16
His films Blaise Pascal (1972) and Cartesius (1974) have the greatest scenery and wardrobe ever. The eerie horror movie soundtrack is also very interesting. Ciro was weirdly reminded of Cosmos: A Personal Voyage (1980).
Roche Biochemical Pathways Updated 2025-07-16
Rolls-Royce Updated 2025-07-16
Romance of the Three Kingdoms event Updated 2025-07-16
Room temperature superconductor Updated 2025-07-16
Cool data embedded in the Bitcoin blockchain Mt. Gox' shutdown Updated 2025-07-16
Mt. Gox was the first Cryptocurrency exchange in existence, and when it shutdowon in Febrauary 2014 because the website was crap and they got hacked, some people were not happy at all about their missing funds!
tx 0540b5dda23ee870330c6b1e18a88c592cf8d847c47f1dc1d5328f46115b12b3 (2014-02-25)
2014-02-25: The day Mt.Gox shut down. Farewell, may even you rest in peace!tx 2374f8575f65763caf6909551c131d3ae45399a73aee638bcbccaebdb1219d67 (2014-02-25):
Fuck you MtGox
Fuck you MtGox
Rtx c00a4a04905a2e8d8dee8a768165aa6bdf842413a8a648462a6349db89cd77f2 (2014-02-27) has an ASCII art of a seal, TODO understand meme:
o
/ |
| \
. | |
.'\` | \|
| \_/ \ \
\____/\/
<3 You Seals!There are also a few Base58 messages referring to Mt Gox, the nicest and most expensive one being to burn addres:which as of 2025 holds 0.014537 BTC burnt on:Many of these transactions also contain other quick messages, e.g.:
- 14x 0.001 BTC transactions starting at tx b170551d4df68d714fa98189c73f61b0c2bc54cafe33a2953fcc0bc11f6aa72a block 287826 (2014-02-26)
- plus one 0.001337 BTC transaction in the middle at tx 6b878716d1d9af0f50de441f318da68121261a5778fd541def4408c0aac531f6 block 287868 (2014-02-26), why not.
- tx e6d4cfbbc45b5e3cfcfa36613b04a8732c7b4606f5dbbd8af3ba06d8f3899fc2 also features a Rickrolling instance.
- tx 10a9bb0625447df044410cf9cd74742ec0bf334d48b4b1f93c10a4a60748bb5d also features
Niggerinside a spendable vanity address: 1Niggerw15VezU6rA7jRBuJt9ceg9VL1jh
F2Pool Updated 2025-07-16
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