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Теория категорий

2019 October 28

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Nick Ivanych
I don't really think that "set theory, group theory, algebra" is absolutely necessary.
You may try with, for example, Battosz book — may be it's not ideal, but it's certainly not bad.
Math will provide you many interesting examples and it would be simplier to study categories.
But it's not strictly necessary.
Well, to be fair, Bartosz does make a lot of references to those things and without a certain background you will have to google them
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Nick Ivanych in Теория категорий
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Well, to be fair, Bartosz does make a lot of references to those things and without a certain background you will have to google them
To be honest, i do not remember very good Bartosz book ;-)
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Oleg ℕizhnik in Теория категорий
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Well, to be fair, Bartosz does make a lot of references to those things and without a certain background you will have to google them
can you please recall some example of this?
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Oleg ℕizhnik in Теория категорий
I have near to nothing experience regarding mentioned areas, still hadn't any issues reading Bartosz's blog.
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( in Теория категорий
Oleg ℕizhnik
can you please recall some example of this?
I think Bartosz used terms like "sets" and "classes" right where he was explaining the notion of small categories. It's not really complicated, but still is a valid example of what I was referring to
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Oleg ℕizhnik in Теория категорий
Well, you don't need to know ZFC set theory properly to understand those things
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( in Теория категорий
I think I'll agree there. I guess what I'm trying to say is that you don't need deep knowledge of those areas, but basic knowledge would help a lot
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Nick Ivanych in Теория категорий
Oleg ℕizhnik
Well, you don't need to know ZFC set theory properly to understand those things
NBG set theory ;-)
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Oleg ℕizhnik in Теория категорий
I suppose wikipedia level will suffice
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Толеген Избасар in Теория категорий
I agree. The question was what is useful in regards to TC. Thats what is useful. The mathematical analysis or mathematical physics is not useful for example, as they deal with concretics rather than abstractions.
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Oleg ℕizhnik in Теория категорий
Толеген Избасар
I agree. The question was what is useful in regards to TC. Thats what is useful. The mathematical analysis or mathematical physics is not useful for example, as they deal with concretics rather than abstractions.
There are people who might disagree
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Толеген Избасар in Теория категорий
You can study TC without any math. Even though other math areas may be useful to understand how proof works in math. Also they might be easier to grasp as they are more concrete.
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Oleg ℕizhnik in Теория категорий
If Alice reads Milewski, she is probably a coder and would be pleased to find haskell examples, if Bob is a physicist, physics examples would be more useful for him, both are likely to have same amount of cathegory theory knowledge
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Oleg ℕizhnik in Теория категорий
So it would be useful to have some profession and some book  using examples from the related domain
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Pika Chu in Теория категорий
FYI Они в МИТе курс по этой книжке в разных вариациях читают.
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Maaf Merepotkan... 🙏 in Теория категорий
Nick Ivanych
I don't really think that "set theory, group theory, algebra" is absolutely necessary.
You may try with, for example, Battosz book — may be it's not ideal, but it's certainly not bad.
Math will provide you many interesting examples and it would be simplier to study categories.
But it's not strictly necessary.
I did read Bartosz. Finished but I feel like I lack of basic math knowledge.

And currently I also watch his videos in youtube. Not finished yet. Still chapter II.

The thing is I have to read the book many times. And also watch with many replay.
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Nick Ivanych in Теория категорий
Maaf Merepotkan... 🙏
I did read Bartosz. Finished but I feel like I lack of basic math knowledge.

And currently I also watch his videos in youtube. Not finished yet. Still chapter II.

The thing is I have to read the book many times. And also watch with many replay.
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2019 October 29

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Nick Ivanych in Теория категорий
Такое вот.
Products and coequalizers in pointed categories
Michael Hoefnagel
https://arxiv.org/abs/1910.12517
Из "main results" —
If C is a pointed category with binary products which satisfies (P), then the product of two normal epimorphisms is normal, and in particular C has normal projections.
#paper
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Михаил Бахтерев in Теория категорий
Maaf Merepotkan... 🙏
I did read Bartosz. Finished but I feel like I lack of basic math knowledge.

And currently I also watch his videos in youtube. Not finished yet. Still chapter II.

The thing is I have to read the book many times. And also watch with many replay.
You should try to take notes and drawings on paper while reading or watching. It really helps. TC is deeply hardwiered in the motion centers of brain, as Milewsky points.
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2019 October 30

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Михаил Бахтерев in Теория категорий
Не подскажете ли, где можно почитать философские (ну, качественные) объяснения того, что такое экспоненциал? Я вот чего не понимаю.

Возьмём категорию Hask. Объекты — это типы, типизированные термы - это морфизмы. Но что тогда такое lambda? Отображение, переводящее терм в форме lambda (x, y) ... в терм в форме lambda x. lambda y ... и "сохранение" его во множестве a -> b -> c? То есть, чисто текстовое такое преобразование? Но это как-то расходится с тем, что про lambda пишут в большинстве других случаев, где lambda — это нечто вроде конструктора кода вычисления.

Что бы такое почитать, чтобы прояснить все детали? С абстрактной точки зрения, конечно, определение очевидно. Но вот концептуально я плыву.
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