Graph representation Updated 2025-07-16
Gridworld AI game Updated 2025-07-16
- github.com/google-deepmind/pushworld 2023 Too combinatorial, gripping makes it so much easier to move stuff around in the real world. But cool nonetheless.
Ciro Santilli's hardware 2023 laptop buy research Updated 2025-07-16
- Dell XPS 15 www.dell.com/en-uk/shop/laptops/12th-gen-intel/spd/xps-15-9520-laptop
- CPU: Intel Core i7-12700H (12th gen)
- Graphics: Nvidia GeForce RTX 3050 Ti
- RAM: 16GB DDR5. Can be upgrated to 32 or 64.
- Display: 15.6-inch 3.5K (3,456 x 2,160), 60Hz
- Storage: 1TB PCIe NVMe M.2 SSD. Can be upgraded to 2TB or 4TB.
- Weight: 1.96 kg
- Price in UK: £1,948.99
- Ubuntu: no
- Tom's guide battery life: 10-hours (web browsing) www.tomsguide.com/reviews/dell-xps-15-oled-2022-review-a-great-macbook-pro-alternative
- Dell XPS 13 www.dell.com/en-uk/shop/laptops/xps-13/spd/xps-13-9315-laptop
- Dell XPS 13 plus
- ThinkPad X1 Carbon Gen 11 (14" Intel) www.lenovo.com/gb/en/p/laptops/thinkpad/thinkpadx1/thinkpad-x1-carbon-gen-11-(14-inch-intel)/len101t0049
Ciro Santilli's hardware Bicycle products Updated 2025-07-16
2022-02: lost my Karrimor REFLEKT, must have fallen off from trouses somewhere.
2022-02: bought Burg Wachter Sold Secure Bike Chain, Lock and Ground Anchor Kit 1m, 10mm chain width: www.amazon.co.uk/Burg-Wachter-Sold-Secure-Gold-Chain/dp/B09MMGL9B7
2022-02 bought Kryptonite Kryptoflex double loop cable 1.2m length 10mm diameter braided steel cable: www.kryptonitelock.com/en/products/product-information/current-key/210818.html
2022-02: bought a Trelock BC 115/110/4 chain white for my saddle after Liv Flourish 2 (2018) the saddle of was stolen at home. Same as this but white: www.trelock.com/en/lock/locks/chain-locks/bc-115-110-4-green. The keys are a bit larger than I'd like.
2021-11: buying a Cateye ViZ450 www.cateye.com/intl/products/safety_lights/TL-LD820/ 51 dollars after CatEye RAPID X2 was stolen. Unfortunately, it is not very compatible with my Topeak saddle bag... the attachment is to wide to fit the saddble bag, and even if it did it is slanted to account for seat tube slant so it would not be very verfical. Arghh, they have futher options on the website: www.cateye.com/intl/products/parts/5342460/ that is the one I need, Clip C-2 or Clip C-1N. On Amazon it didn't have clear choices for that... mine came with the BracketSP-15. Ah, can buy on Amazon for 3 dollars, OK then.
2021-11: COZYROOMY multitool broke apart already, like before, but much sooner this time. What a piece of junk!!! Buying the Topeak Mini 18+ Bike Multitool www.topeak.com/global/en/products/75-Mini-Tools/173-mini-18+ Has a spoke wrench.
2021-09: COZYROOMY multitool stolen, even though it was completely in pieces already. 2021-09-21 12:30PM discovered, seat bag open, one tool on floor, and some leftovers inside, but black bag gone. Bicycle last seen 2021-09-20 6PM. Would likely have spotted it if it had happened before. Bicycle last used: 2021-09-19 6PM. Would almost for sure have seen it if it had happened by then. Rebought it.
2021-07 Topeak MTS Trunkbag EX Strap Type www.topeak.com/global/en/products/192-Rear-Rack-Bags/859-MTX-TRUNKBAG-EX Fit nicely on the back of the Kross bicycle (2017). 8L. Originally to carry some extra food and water on a long summer trip. 36 pounds.
2020-11-30: Bought more "Finish Line DRY Teflon Bicycle Chain Lube" 8oz/240ml www.amazon.com/dp/B00Z779GMO/ after previous disaster with the bottle because lock is a bit hard to open.
2020-11-30 WD-40 Bike, All Conditions Lube Bicycle Lubricant, 250ml. Markings: "Contains PTFE". www.amazon.com/dp/B00O8QF3PY Sprays out of bottle, so very thin.
2020-11: Park Tool CC-2 Chain Checker Tool www.amazon.co.uk/dp/B000OZFILW 24 pounds www.parktool.com/product/chain-checker-cc-2
2020-04: www.amazon.co.uk/gp/product/B014LC7HS0 "Park Tool HPG-1 High Performance Grease", 113 g, blue. www.parktool.com/product/high-performance-grease-hpg-1#tabbed-section | www.parktool.com/assets/doc/product/HPG-1_SDS.pdf
2020-02: CatEye AMPP500 45 pounds www.cateye.com/intl/products/headlights/HL-EL085RC/ High mode 500 lumens: 1.5hrs, Daytime HyperConstant mode 500/250 lumens: 5hrs. 2020-11: noticed it was cracked on top front between button and light, I think I dropped it the other day from waist height.
2020-02: Karrimor REFLEKT Band 2 pounds from Sports Direct to replace old that I destroyed by playing with it with hands on work desk www.karrimor.com/karrimor-reflect-band-765007
2020-01: Muc-Off Drivetrain Cleaner - 500ml www.halfords.com/cycling/bike-maintenance/bike-cleaning/muc-off-drivetrain-cleaner-500ml
2020-01: Halfords Microfibre Heavy Duty Cloths www.halfords.com/motoring/car-cleaning/sponges-brushes-buckets/halfords-microfibre-heavy-duty-cloths (archive) 87% polyester, 13% polyamide.
2019-12: www.amazon.co.uk/gp/product/B07GQSXN8B SENZEAL Bicycle Spoke Wrench Tool Spoke Key Spanner 6 in 1 for Bike Wheel Cycle Wrench 10-15 Gauge. TODO 2024: can't find those for the life in me.
2019-12: Halford's Bike Hut Chain Cleaning Kit: www.halfords.com/cycling/bike-maintenance/bike-cleaning/bikehut-chain-cleaning-kit 18 pounds. GCN video using it: www.youtube.com/watch?v=KM6mzE5lQ0w Review video saying it is useless: www.youtube.com/watch?v=rCo41pftAjU
2019-11: Multitool: www.amazon.co.uk/dp/B07MW3K2GK "COZYROOMY Bike Repair Kits - Bicycle tool kit with 10 in 1 Multi-Function Bike Tool, multi-purpose bone wrench And related spare tools, 1 Portable tool bag, 6 Month Warranty". No spoke wrench unfortunately. But does have 15mm bone wrench, which opens Kross front wheel. Some months later, the thing came apart, quality was a bit shit. But I kept it in the saddle bag anyways for a long time, and just used it by putting part of it manually together.
2019-11: "CatEye RAPID X2" real lights, 40 dollars. Hopefully to increase side visibility at night, and day visibility on fast roads when cycling further on weekends. www.cateye.com/intl/products/safety_lights/TL-LD710-R/ (archive) USB rechargeable. 80 lumens in high mode lasting 1 hour, 5 hours in low mode, 30 hours flashing, 16 hours rapid/pulse. Lost 2021-11 in a big city, didn't know the path well, had to cross a bunch of streets, was on back of back bag, likely stolen.
2019-10 Finish Line Dry Teflon Tube www.amazon.com/dp/B00B704LZW (archive) Tube broke while opening the first day. I glued it with some superglue, but two months later found it leaked into my "oils bag", so I threw it away... it must have penetrated through the super glue.
2019-08: "CatEye CA475RAPMIN Rapid Mini Rear Lights and Reflectors, Black" stolen: www.amazon.co.uk/dp/B01I4193PY (archive). Very good quality. Those USB rechargeable lights you just have got to take off with you whenever parked in town or else drug addicts will steal them because they are easy to remove for recharging. Tempted to just stick to dynamo ones that are screwed in. Re-bought original back light: AXA Basta, was a bit different from previous one, cannot take in lamps anymore, even though there is the plastic casing for them! Just not metal / wires.
Ciro Santilli's hardware ELEGOO Upgraded Electronics Fun Kit Updated 2025-07-27
2022-10 ELEGOO Upgraded Electronics Fun Kit www.elegoo.com/products/elegoo-electronics-fun-kits-4-versions Manuals:
- Elegoo Breadboard power supply module MB‐V2:TODO center positive or center negative?Does not come with AC adapter, getting this one: www.amazon.co.uk/dp/B08ZN476FW output: DC 9V 1A Power Supply Adapter, Plug 5.5mm x 2.1mm, Center Positive,B rand: Security-01, input: AC 100-240V 50/60 Hz, Cable length: 1.8mParts list from the ZIP:
- resistors:
- 1n4007 General Purpose Rectifier
- 22pf 104 Ceramic Capacitor
- 4N35 optocoupler
- 74HC595 8-bit serial-in, serial or parallel-out shift register with output latches; 3-state
- Active buzzer
- Buttons
- CDS-55 Photoresistor
- Electrolytic Capacitor
- Focusens MF52D 103f 3950 thermistor. Beta value 25/50 Celcius: 3950. R_25: I measured 9.61 k Ohms. The number 103 they document as:These descriptions are weird, but ChatGPT has the theory that the first two digits are actual values, and the last is multiplier, so which makes 10k.
but I have no idea how that maps to 10 k Ohms. - PN2222 General Purpose Transistor
- Passive buzzer
- 3386p Bourns Precision Potentiometer - 1 103T: from 0 to 10k Ohms, measured with multimeter. According to the manual the "103" mean 10 k oms, which is consistent with our measurement. "P 103" is etched into the part.
- LEDs:
Ciro Santilli's hardware Mechanical and electrical tools Updated 2025-07-16
2020-01 www.amazon.co.uk/dp/B07D318N7Z
2020-01 "Heat Gun, SEEKONE Professional 2000W 50℃- 600℃ Variable Temperature Control Hot Air Gun Kit with 2 Temperature Modes 7 Accessories for D" www.amazon.com/dp/B078S5QMFG Initially for for cell phone repair, but later learnt they are also useful for heat shrink.
2020-11 BOA 13-2612 Strap Wrench, 6-Inch Capacity 8-Inch Long Lever www.amazon.com/dp/B00096JDKS Official: www.boatoolcorp.com/our-products/boa-constrictor-range/boa-constrictor/
2019-09 "Draper Redline 68001 160 mm Heavy Duty Pliers Set with Soft Grip Handles (3-Piece)" web.archive.org/web/20190903191215/https://www.amazon.co.uk/dp/B071JL6LLL (archive)
2019-08: www.amazon.co.uk/dp/B000LFRYG2 (archive) "Silverline SP1236 Combination Spanner, 8-19 mm - 12 Pieces" 8.48 pounds. Because I needed the 15mm for bike pedal, and the price of 1 and the full set were very close.
6 10/11/12/13/14/17 mm Combination Wrench Set WRENCH SET COMBINATION Open-Ended Spanner/Ring Spanner Set www.amazon.co.uk/dp/B07BZLVGX8 (archive) But they sent one wrong, 8 instead of 11. Chrome Vanadium Steel. Markings: "DROP FORGED A". Quality feels crappy, not very smooth.
2017: Teng 621011 Double Open Ended Spanner 10x11mm www.amazon.co.uk/dp/B0001P0VP8 (archive)
2017: Magnusson AMS49 5M TAPE MEASURE 5m retractable flexible rule. www.screwfix.com/p/magnusson-ams49-5m-tape-measure/5315v (archive)
Ciro Santilli's hardware Motorola Moto G6 Play (2018) Updated 2025-07-16
www.gsmarena.com/motorola_moto_g6_play-9002.php Upgradable to Android 9.
2023-10: unable to connect to Giffgaff. "Network unavailable". Same SIM works in other phones. So annoying. Update APN to match: www.giffgaff.com/help/articles/internet-apn-settings-guide. Went next to a tower and then got signal. So the receiver is much worse than the pixel one. Vibration appears to be broken.
Group of Lie type Updated 2025-07-16
In the classification of finite simple groups, groups of Lie type are a set of infinite families of simple lie groups. These are the other infinite families besides te cyclic groups and alternating groups.
A decent list at: en.wikipedia.org/wiki/List_of_finite_simple_groups, en.wikipedia.org/wiki/Group_of_Lie_type is just too unclear. The groups of Lie type can be subdivided into:
- Chevalley groups
- TODO the rest
The first in this family discovered were a subset of the Chevalley groups by Galois: , so it might be a good first one to try and understand what it looks like.
TODO understand intuitively why they are called of Lie type. Their names , seem to correspond to the members of the classification of simple Lie groups which are also named like that.
But they are of course related to Lie groups, and as suggested at Video "Yang-Mills 1 by David Metzler (2011)" part 2, the continuity actually simplifies things.
Primarily bought to make borlotti beans!!!
Ciro Santilli's hardware Samsung MZVLB512HAJQ-000L7 512GB SSD Updated 2025-07-16
PCIe TLC OPAL2.
www.samsung.com/semiconductor/global.semi/file/resource/2018/05/PM981_M.2_SSD_Datasheet_v1.3_for_General.pdf | web.archive.org/web/20181224225410/https://www.samsung.com/semiconductor/global.semi/file/resource/2018/05/PM981_M.2_SSD_Datasheet_v1.3_for_General.pdf
sudo hdparm -Tt /dev/nvme0n1p5 on Ubuntu 20.04: Timing cached reads: 29812 MB in 1.99 seconds = 15007.00 MB/sec
HDIO_DRIVE_CMD(identify) failed: Inappropriate ioctl for device
Timing buffered disk reads: 6328 MB in 3.00 seconds = 2109.00 MB/sec Ciro Santilli's hardware Skullcandy Smokin' Buds 2 Updated 2025-07-16
2023-07: one of the sides broke near center, rebuying.
2021-07: wire half broke near connector, only works in some positions. The funny thing is: only voices seem to be blocked out! Rebuying.
2021-06: a small bottom piece of the left earpiece broke. Wire seems find, that is like a little extension to protect wire. Let's see for how long.
2020-20: wires at one of ears broke, not sure how.
Look they looked exactly like: "Skullcandy Smokin' Buds 2 In-Ear Audio Earbud Headphones with In-Line Microphone - Black".
Re-buying that one 10 pounds:
Tech specs:
Connection Type: 3.5mm AUX CableImpedence: 32 ohmsDriver Diameter: 9mmSound Pressure Level: 95 dB (1mW/500Hz)Frequency Response: 20kHz - 20HzHeadphone Type: In-Ear
Guqin player Updated 2025-07-16
Ciro Santilli's hardware TP Link ARCHER VR2800 Updated 2025-07-16
Manual: www.tp-link.com/uk/support/download/archer-vr2800/ In particular, the user guide: static.tp-link.com/1910012125_Archer%20VR2800(EU)_V1_UG.pdf
Admin IP address: 192.168.1.1/ It also works over Wifi and people don't know how to disable that: community.tp-link.com/en/home/forum/topic/1460
Ciro Santilli's legs sometimes itch when he runs Updated 2025-07-16
Ciro Santilli has an undiagnozed condition where his upper legs and lower torso often start to itch when he runs, to the point of being extremely annoying and removing all pleasure form the activity.
If some doctor knows why this could be, please tell him!!!
The problem is a bit hard to reproduce however, and Ciro hasn't been able to determine which exact condition triggers it: temperature, nutrition, something else?
Ciro believes that this is not chiefly due to transpiration, but rather to the impact motion that running does on the muscles, as he has felt something similar on his arms some times while cycling in very rough terrain, which made his arms shake in a similar fashion. or for example if he has a water bottle on a tightly tied backpack that rubs his back, then the back itches at that point.
Also, running on a threadmill is not a problem at all. Ciro believes that this is because the threadmill is better amortized, and therefore does not cause the same mechanical stress required to create the itching as running on pavement.
Interestingly, Ciro didn't feel that at all when he played soccer enthusiastically as a child, and he was one of the fastest runners of the group for sure at that time. So he's not sure if it started when he got older, or if it is just because the difference in workloads between soccer and running.
youtu.be/PNgYW5N95z8?t=945 "My back itches" after riding on a bumpy makeshift motorcycle.
Hazard (computer architecture) Updated 2025-07-16
Ciro Santilli's undergrad studies at the University of São Paulo Updated 2025-07-16
Ciro's official diploma from the University of São Paulo read "Automation and Control Engineer at the Polytechnic School of the University of São Paulo".
The University of São Paulo had been elected the best South American university in the Times Ranking 2013 (archive) in all subjects.
Ciro finished the course with honors of "The Best Student in Automation and Control of the year 2013".
Ciro didn´t learn basically any control engineering however unfortunately. He did only the 3 base years of the electrical engineering course, and the rest got lost on stupid politics of having to go back to do 6 months from France to validate his Brazilian degree, see also: Section "Don't force international exchange students to come back early".
Ciro's call hierarchy notation Updated 2025-07-16
This is a simple hierarchical plaintext notation Ciro Santilli created to explain programs to himself.
It is usuall created by doing searches in an IDE, and then manually selecting the information of interest.
It attempts to capture intuitive information not only of the call graph itself, including callbacks, but of when things get called or not, by the addition of some context code.
For example, consider the following pseudocode:Supose that we are interested in determining what calls
f1() {
}
f2(i) {
if (i > 5) {
f1()
}
}
f3() {
f1()
f2_2()
}
f2_2() {
for (i = 0; i < 10; i++) {
f2(i)
}
}
main() {
f2_2()
f3()
}f1.Then a reasonable call hierarchy for
f1 would be:f2(i)
if (i > 5) {
f1()
f2_2()
for (i = 0; i < 10; i++) {
f2(i)
main
f3
f3()
main()Some general principles:
Classical limit Updated 2025-07-16
The idea tha taking the limit of the non-classical theories for certain parameters (relativity and quantum mechanics) should lead to the classical theory.
It appears that classical limit is only very strict for relativity. For quantum mechanics it is much more hand-wavy thing. See also: Subtle is the Lord by Abraham Pais (1982) page 55.
Classical mechanics Updated 2025-07-16
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