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Which boundary conditions lead to existence and uniqueness of a second order PDE by 
Ciro Santilli 40 Updated 2025-07-16
Ciro Santilli 40 Updated 2025-07-16www.cns.gatech.edu/~predrag/courses/PHYS-6124-12/StGoChap6.pdf 6.1 "Classification of PDE's" clarifies which boundary conditions are needed for existence and uniqueness of each type of second order of PDE:
The name does not imply regular by default. For regular ones, you should say "regular polytope".
Convex hull of all (Cartesian product power) D-tuples, e.g. in 3D:
( 1, 1, 1)
( 1, 1, -1)
( 1, -1, 1)
( 1, -1, -1)
(-1, 1, 1)
(-1, 1, -1)
(-1, -1, 1)
(-1, -1, -1)Ciro Santilli is very fond of this result: the beauty of mathematics.
How can so much complexity come out from so few rules?
How can the proof be so long (thousands of papers)?? Surprise!!
And to top if all off, the awesomely named monster group could have a relationship with string theory via the monstrous moonshine?
The classification contains:
- cyclic groups: infinitely many, one for each prime order. Non-prime orders are not simple. These are the only Abelian ones.
- alternating groups of order 4 or greater: infinitely many
- groups of Lie type: a contains several infinite families
- sporadic groups: 26 or 27 of them depending on definitions
Simple Groups - Abstract Algebra by Socratica (2018)
Source. Good quick overview.Besides the understandable Wikipedia definition, Video "Simple Groups - Abstract Algebra by Socratica (2018)" gives an understandable one:
Given a finite group and a simple group , find all groups such that is a normal subgroup of and .
We don't really know how to make up larger groups from smaller simple groups, which would complete the classification of finite groups:
In particular, this is hard because you can't just take the direct product of groups to retrieve the original group: Section "Relationship between the quotient group and direct products".
Basically the same as classical mechanics.
Ciro Santilli's hardware House 2018-01 Aluminium extractor filter by Ciro Santilli 40 Updated 2025-07-16
Ciro Santilli 40 Updated 2025-07-16This is the exact model: shop.elica.com/en/accessori/filtro-grassi-in-alluminio-cod-gf03fc.html | web.archive.org/web/20190707053526/https://shop.elica.com/en/accessori/filtro-grassi-in-alluminio-cod-gf03fc.html
Searching by th epart name "GF03FC" leads to other sellers besides Elica however, which could reduce shipping costs: www.cookerhoodsupplies.co.uk/filters-and-lamps/188-metal-grease-filter-gf03fc.html
Brand on filter itself: "ARMA Filtre a.s." based on markings: www.armafiltre.com.tr/uygulamalar/7/3/en/Home-Appliances.html Cannot find any model on website however... looks like Elica's B2B supplier only.
July 2019 message:
Aluminium extractor filter for 208298104403Hi there,I'm trying to buy a spare aluminium extractor filter for an Elica extractor, but I can't find the right size on the website.My 12NC is : 208298104403My filter looks a lot like this: shop.elica.com/en/accessori/filtro-grassi-in-alluminio-cod-GRI0077330A.html but the dimensions are different: I measured 45.9cm x 17.6cm on my old one.Do you have that for sale?
Brand according to documents: SMEG.
Most similar models I an find: www.smeguk.com/products/UKC8173N1F and www.smeguk.com/products/UKC81721F, the keyword are "built-in" and "integrated", other very similar ones: www.smeguk.com/refrigerators/built-in
Looks like this: www.youtube.com/watch?v=4c_LBVnU4ec and that's how to unclog the drain.
2020-11-28: defrost. Some small Styrofoam was broken lose from top, noticed small burn or rust marks on top grid nearby.
Looks a lot like: Bristan Monza EF Sink Mixer Chrome www.bathroomsensations.co.uk/Bristan-Monza-EF-Sink-Mixer-Chrome.html
How to open: www.youtube.com/watch?v=oHTpOG1Uhzw
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
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