howling

Yes it's not necessary for them to be losing in the long term for Jane Street to be profitable, but I suspect they are.

> The other mitigation strategy is: just buy some puts.

I wonder who are the counterparties selling puts to Jane Street. My cynical view is that they are losing overall but the traders don't care because they are winning in short term (when nothing happens) and may have already changed their job when the market crashes.

Normal currying describes an isomorphism between functions of type (A x B) -> C and functions of type A -> (B -> C). With dependent types, we can have an isomorphism between functions of type ((a : A) x (b : P(a))) -> Q(a, b) and functions of type (a : A) -> ((b : P(a)) -> Q(a, b)). What your article proves is a bit less generic with Q doesn't vary accoring to a and b; i.e. an isomorphism between ((a : A) x (b : P(a))) -> Q and functions of type (a : A) -> ((b : P(a)) -> Q).

Personally, I find the title to be slightly misleading as the proof is essentially just (un)currying for dependently typed function.

His python code can be shorten to

  from math import *
  prod(map(factorial, l))

which isn't much longer than his J code especially if you count the number of tokens rather than the number of characters as the J code uses ridiculously terse names.

Standard application of selection bias. People that don't "turn up just fine" don't go to college or browse HN.

I can see how to do it with a cube now but I don't think it works for general paralleleliped as it has 3 pair of different faces and a naive way of dividing it into 6 tetrahedra would cut each face into two triangles so we get 3 sets of 4 congruent triangles. You can't allocate 3 sets of 4 congruent triangles into 6 equal groups.

While your volume formula is correct, I don't see a way to cut a general parallepiped into 6 identical tetrahdtra. In fact, I don't see how it can be accomplished with a cube.

Does she have any writings online that describe those nasty semantic edge-cases?

https://chemguide.co.uk is great for A-level chemistry.

What Nina actually posted:

https://mimiandeunice.com/2018/11/07/the-jenndra-identitty-c...

https://blog.ninapaley.com/2018/02/07/gender_colonialism/

Random ballot is different from sortition.

There are quite a few voting systems that removes/minimizes incentive of gerrymandering. My favourite is https://en.wikipedia.org/wiki/Random_ballot .

The 3d equivalent of a circle is a sphere, which is also impossible to escape from in 3d.

I think the prerequisite for "Category Theory in Context" is a grasp of basic category theory ((co-)limits, Yoneda lemma, adjoint functor theorems, etc). You should also have some interest in an abstract maths field that requires all these category theory machinery. So a graduate student in abstract maths sounds about right.

And how do you prove that a totally-ordered, Dedekind-complete, Archimedean field does not lead to contradiction besides constructing it explicitly by bootstrapping from natural numbers?

relevant xkcd: https://xkcd.com/2028/

Keeping your wealth as money is also gambling (you're betting against high inflation rate).

Okay, to be pedantic, pseudo-polynomial time.

Actually, the knapsack problem allows taking an item more than once. The problem described in the blog is the 0-1 knapsack problem which can be solved in polynomial time.

Not an expert but I think it is only suitable for text file since most diff algorithms assume the files are made of not-very-long lines.

Representation theory is about study of functors between category of vector spaces and category of interest, which is quite different from the problem of different representations of a triangle.

The article elaborates on this point a bit:

> Like pipes in UNIX, the functions are clever enough to be performant when composed together–we don’t traverse the whole list and generate a new list each time, each item is generated on demand. In fact, due to stream fusion, the code will be compiled into one fast loop.

I imagine it is hard to do the same optimization in a non-lazy language.

The definition is correct. A monad is an endofunctor with return and join functions. Just like a monoid in the category of sets is a set with identity and multiplication.

I would have written two functions instead where one takes a default argument and the other returns None if the list is empty.

In pseudo-Haskell notation:

    min1 : Int -> List Int -> Int
    min1 def Nil = def
    min1 def (Cons x xs) = min1 (def if def <= x else x) xs

    min : List Int -> Maybe Int
    min Nil = None
    min (Cons x xs) = min1 x xs

The article (as many others) fails to address the single most important question in the palm oil debate.

What alternatives are there if we are to avoid palm oil? How are they more environmentally friendly?

> It was only 282 years ago that Euler presented in his textbooks the exact formula for the volume of a sphere

It's strange that Fermat's Library stated this since the formula for volume of sphere was discovered by Archimedes more than 2000 years ago.

[1]: https://en.wikipedia.org/wiki/On_the_Sphere_and_Cylinder

You can just disallow that?

The best case scenario to a customer in a year is that he pays exactly 0, which happens with probability (0.9)^12.

A potential way to solve this is randomness. Instead of every customer paying $3 per month, every customer has a 10% chance of paying $30 per month.