Not Just Bikes Updated 2025-07-16
Rho Updated 2025-07-16
General linear group Updated 2025-07-16
Non-invertible are excluded "because" otherwise it would not form a group (every element must have an inverse). This is therefore the largest possible group under matrix multiplication, other matrix multiplication groups being subgroups of it.
Greenberger-Horne-Zeilinger state Updated 2025-07-16
Group extension problem Updated 2025-07-16
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".
Maxwell's equations in curved spacetime Updated 2025-07-16
Combination of electromagnetism and general relativity. Unlike combining quantum mechanics and general relativity, this combination was easier.
TODO any experiments of interest at all?
Software reverse engineering tool Updated 2025-07-16
ANN model Updated 2025-07-16
Equivalence between Lagrangian and Hamiltonian formalisms Updated 2025-07-16
Grinding for software interviews Updated 2025-07-16
If your kids are about to starve, fine, do it.
But otherwise, Ciro Santilli will not, ever, spend his time drilling programmer competition problems to join a company, life is too short for that.
Life is too short for that. Companies must either notice that you can make amazing open source software projects or contributions, and hire you for that, or they must fuck off.
Guns Are Worthless Updated 2025-07-16
Punycode inscription Updated 2025-07-16
There seems to be nothing of particular artistic value as far as we've seen so far, the only interest in such tokens seems to be that:
- there are some examples that came earlier than those in the Bitcoin blockchain, notably a bit earlier than Section "BitLen"
- Namecoin is a NFT system unlike Bitcoin which is fungible, so those assets are naturally tradable
RimWorld Updated 2025-07-16
Sexual arousal Updated 2025-07-16
Analects translation by Robert Eno (2015) 16.7:
Antimicrobial Updated 2025-07-16
Unit and system tests Updated 2025-07-16
Dwarf Fortress Updated 2025-07-16
Limited series Updated 2025-07-16
If you are going to make a television series, do make it a limited one. Plan one story, and execute it amazingly. Don't let things drag on and on.
Matrix representation of a linear form Updated 2025-07-16
For the typical case of a linear form over , the form can be seen just as a row vector with n elements, the full form being specified by the value of each of the basis vectors.
SQL contiguous ranges Updated 2025-07-16
stackoverflow.com/questions/17046204/how-to-find-the-boundaries-of-groups-of-contiguous-sequential-numbers/17046749#17046749 just works, even in SQLite which supports all quoting types known to man including
[] for compatibility with insane RDBMSs!Here's a slightly saner version:
rm -f tmp.sqlite
sqlite3 tmp.sqlite "create table mytable (id integer primary key autoincrement, number integer, status integer)"
sqlite3 tmp.sqlite <<EOF
insert into mytable(number, status) values
(100,0),
(101,0),
(102,0),
(103,0),
(104,1),
(105,1),
(106,0),
(107,0),
(1014,0),
(1015,0),
(1016,1),
(1017,0)
EOF
sqlite3 tmp.sqlite <<EOF
SELECT
MIN(id) AS "id",
MIN(number) AS "from",
MAX(number) AS "to"
FROM (
SELECT ROW_NUMBER() OVER (ORDER BY number) - number AS grp, id, number
FROM mytable
WHERE status = 0
)
GROUP BY grp
ORDER BY MIN(number)
EOFoutput:
1|100|103
7|106|107
9|1014|1015
12|1017|1017To get only groups of length greater than 1:
sqlite3 tmp.sqlite <<EOF
SELECT "id", "from", "to", "to" - "from" + 1 as "len" FROM (
SELECT
MIN("id") AS "id",
MIN(number) AS "from",
MAX(number) AS "to"
FROM (
SELECT ROW_NUMBER() OVER (ORDER BY "number") - "number" AS "grp", "id", "number"
FROM "mytable"
WHERE "status" = 0
)
GROUP BY "grp"
ORDER BY MIN("number")
) WHERE "len" > 1
EOFOutput:
1|100|103|4
7|106|107|2
9|1014|1015|2 Unlisted articles are being shown, click here to show only listed articles.