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beroal

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On when linear maps and matrices were introduced [Aug. 3rd, 2020|01:39 pm]
beroal
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One striking feature of Noether's 1929 paper occurred in a footnote: “As B. L. van der Waerden has communicated to me, one can obtain an invariant connection, independent of the specific choice of basis, by separating the concepts linear transformation and matrix. A linear transformation is a homomorphism of two modules of linear forms; a matrix is an expression (the representation) of this homomorphism by a definite choice of basis” [76,670]. Here we have the essential modern connection between the notions of linear transformation, matrix, and module (or vector space). Two years later, van der Waerden's insight about the proper way of viewing that connection was presented to a much wider audience in his textbook.

Moore, Gregory H. “The Axiomatization of Linear Algebra: 1875-1940.” Historia Mathematica, volume 22, issue 3, 1995, pp. 262–303. ScienceDirect, doi:10.1006/hmat.1995.1025.
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in English [Jul. 1st, 2020|12:00 am]
beroal
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Welcome!

Posts in English in this blog: HTML; Atom.

My favorite links in


OpenSearch plugin for searching on

Short proofs in Coq.

test link
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по-русски [Jun. 1st, 2020|12:00 am]
beroal
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Добро пожаловать!

Для обратной связи пишите сюда комментарии. Если я не добавляю вас в друзья, это не значит, что я вас не читаю.

Поисковые системы на платформе Google Custom Search Engine:
против мошенничества

only Haskell (the programming language)

OpenSearch plugin (то есть для Firefox) для поиска по:

Математические доказательства на языке Coq. Всякая мелочь, среди крупных модулей можно выделить CategoryTheory, IntBipart (определение целых чисел), TakeDrop («take» и «drop» из Haskell.Data.List).

Лента выбранных мною из чужих блогов записей:


У меня есть личный веб-сайт.
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brackets and quotation characters in Unicode [May. 19th, 2020|01:02 pm]
beroal
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Recently I busied myself with finding a list of brackets and quotation characters and their correspondence in the Unicode Character Database. By “brackets” I mean all kinds of brackets: round, square, curly, etc. Though the database provides necessary information, it has some quirks.

to be continuedCollapse )
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Кобол [Apr. 29th, 2020|10:47 am]
beroal
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По-моему, никто не написал настоящую причину долгожительства Кобола. Причина не в том, что существует много программного кода на Коболе. Программист нужен только для того, чтобы писать новый программный код. Даже если он «дорабатывает» программу, он выбрасывает кусок кода и вписывает на его место новый. Это крайность, скажем, пишет новую функцию. Для этого нужно знать только интерфейс существующего кода, через который функция с ним взаимодействует, что требует больше прикладных знаний, чем знаний япа. В общем, писать на Коболе не требуется.

Настоящая проблема в том, что соединять программы, написанные на разных япах — это занятие для людей с крепкими нервами и свободным временем, и для одной функции просто не окупается. Ещё причина в том, что программы не модульны. Причём это истинно и практически для всех современных япов. Ку-ку.
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This is what you get for using PHP [Feb. 27th, 2020|05:05 pm]
beroal
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I want to save this post for history. This was a question on Computer Science Stack Exchange, and it was deleted, but it is still an opinion and experience of a living programmer.

to be continuedCollapse )
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Linux system call speedup [Nov. 16th, 2019|03:35 pm]
beroal
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Trying to measure the overhead cost of Linux system calls, I got the following strange result:
>./syscall.x
getting time time, ns: 30
syscall time, ns: 740 180 170 170 160 160 160 160 160 160 170 160 160 160 160 160 170 160 160 160 170 160 160 160 170 160 160 160 170 160 160 160 160 160 160 160 160 160 160 160 160 170 160 160 160 170 160 160 160 170 160 160 160 160 160 160 170 160 160 160 170 160 160 160


to be continuedCollapse )
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more medieval logic in contemporary education: Microsoft [Oct. 15th, 2019|12:38 am]
beroal
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In the course “DEV262x Logic and Computational Thinking” from Microsoft, students learn categorical syllogisms. How cute. I mean, Microsoft should know better.
Forms of Categorical Syllogisms

During the Middle Ages, logicians assigned Latin names to the fifteen forms of syllogism first proved valid by Aristotle. These syllogisms were arranged into four groups known as “figures.” The exact logical form for a syllogism is specified by giving the type (A, E, I, or O) for each sentence followed by the number of the syllogism’s figure.
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logic in France [Aug. 23rd, 2019|10:40 am]
beroal
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In France, the discipline of logic has traditionally been ignored in university-level scientific studies. This follows, undoubtedly, from the recent history of mathe­matics in our country which was dominated, for a long while, by the Bourbaki school for whom logic was not, as we know, a strong point.

Krivine, Jean-Louis. Foreword. Mathematical Logic: A Course with Exercises. By René Cori and Daniel Lascar. Trans. Donald H. Pelletier. Oxford: Oxford UP, 2000. Print.

First published in French as Logique mathématique
© Masson, Editeur, Paris, 1993
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An invitation to Secure Scuttlebutt (SSB) [Jun. 28th, 2019|09:26 pm]
beroal
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I invite you to Secure Scuttlebutt (SSB), a serverless social network, where nobody can deprive you of the access to the network or delete your information and only you decide who to read and what to retransmit.

Unfortunately, the part “only you decide who to read” works the opposite way: people will not read you until they know about you. This is the reason few people read novices in the network. I can help you: I will read you and retransmit your information. If you are interested, follow the guide below.

to be continuedCollapse )
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