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Ivano Pagano
"I always write code perfectly the first time" ~ No One Ever
"I always write code perfectly the first time" ~ No One Ever


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Eccoci di nuovo, in attesa delle vostre proposte
Call for papers aperta da domani

And here we come again, open for your proposals
Call For papers open from tomorrow

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Utile per chi spesso si trova a ripulire la cache di ivy

Useful for those who frequently need to clean the ivy cache

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This should become a must watch for every Scala "enterprise" developer.

Very interesting points, many which need to be mentioned more often, especially to newcomers:

- You don't need to be, or become, a FP (functional programming) wizard to be productive in Scala
- Sometimes, leveraging existing battle-tested Java libraries is the best way to go
- Don't feel intimidated by the vastness of the Scala language
- You don't have to use every single Scala feature ;-) - Similarly, sometimes "verbose" (boring) code is preferable over succinct / elegant ("clever") code; which not everybody in the team understands

... among many other good points.

(By Scala "enterprise" developer I mean: anyone planning to use Scala on a team in an "enterprise" setting . As opposed to solo-project, hobby or academic research)

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Maryam Mirzakhani, 1977 - 2017

She died yesterday, a mathematician who had not yet reached the height of her powers: the first Fields medalist from Iran, and also the first woman to win that honor. Here's what I wrote when she won:

As a child in Tehran, she didn't intend to become a mathematician - she just wanted to read every book she could find! She also watched television biographies of famous women like Marie Curie and Helen Keller. She started wanting to do something great... maybe become a writer.

She finished elementary school while the Iran-Iraq war was ending, and took a test that got her into a special middle school for girls. She did poorly in math her first year, and it undermined her confidence. “I lost my interest in math," she said.

But the next year she had a better teacher, and she fell in love with the subject. She and a friend became the first women on Iranian math Olympiad team. She won a gold medal the first year, and got a perfect score the next year.

After getting finishing her undergraduate work at Sharif University in Tehran in 1999, she went on to grad school at Harvard. There she met Curtis McMullen, a Fields medalist who works on hyperbolic geometry and related topics.

Hyperbolic geometry is about curved surfaces where the angles of a triangle add up to less than 180 degrees, like the surface of a saddle. It's more interesting than Euclidean geometry, or the geometry of a sphere. One reason is that if you have a doughnut-shaped thing with 2 or more holes, there are many ways to give it a hyperbolic geometry where its curvature is the same at each point. These shapes stand at the meeting-point of many roads in math. They are simple enough that we can understand them in amazing detail - yet complicated enough to provoke endless study.

Maryam Mirzakhani took a course from McMullen and started asking him lots of questions. “She had a sort of daring imagination,” he later said. “She would formulate in her mind an imaginary picture of what must be going on, then come to my office and describe it. At the end, she would turn to me and say, ‘Is it right?’ I was always very flattered that she thought I would know.”

Here's a question nobody knew the answer to. If an ant walks on a flat Euclidean plane never turning right or left, it'll move along a straight line and never get back where it started. If it does this on a sphere, it will get back where it started: it will go around a circle. If it does this on a hyperbolic surface, it may or may not get back where it started. If it gets back to where it started, facing the same direction, the curve it moves along is called a closed geodesic.

The ant can go around a closed geodesic over and over. But say we let it go around just once: then we call its path a simple closed geodesic. We can measure the length of this curve. And we can ask: how many simple closed geodesics are there with length less than some number L?

There are always only finitely many - unlike on the sphere, where the ant can march off in any direction and get back where it started after a certain distance. But how many?

In her Ph.D. thesis, Mirzakhani figured out a formula for how many. It's not an exact formula, just an 'asymptotic' one, an approximation that becomes good when L becomes large. She showed the number of simple closed geodesics of length less than L is asymptotic to some number times L to the power 6g-6, where g is the number of holes in your doughnut.

She boiled her proof down to a 29-page argument, which was published in one of the most prestigious math journals:

• Maryam Mirzakhani, Growth of the number of simple closed geodesics on hyperbolic surfaces, Annals of Mathematics 168 (2008), 97–125,

This is a classic piece of math: simple yet deep. The statement is simple, but the proof uses many branches of math that meet at this crossroads.

What matters is not just knowing that the statement is true: it's the new view of reality you gain by understanding why it's true. I don't understand why this particular result is true, but I know that's how it works. For example, her ideas also gave here a new proof of a conjecture by the physicist Edward Witten, which came up in his work on string theory!

This is just one of the first things Mirzakhani did. She's now a professor at Stanford.

"I don't have any particular recipe," she said. "It is the reason why doing research is challenging as well as attractive. It is like being lost in a jungle and trying to use all the knowledge that you can gather to come up with some new tricks, and with some luck you might find a way out."

She has a lot left to think about. There are problems she has been thinking about for more than a decade. "And still there’s not much I can do about them," she said.

"I can see that without being excited mathematics can look pointless and cold. The beauty of mathematics only shows itself to more patient followers."

I got some of my quotes from here:

and some from here:

They're both good to read. For a mathematically informed obituary, see this by Terry Tao:

The animated gif is a clip from this video:

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Midyear updates
Midyear updates
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I'm really sorry, but I mistakenly banned one user with a post that looked absolutely ok.
We're so buried with spam that I clicked on the wrong post, and I want to apologize with the victim of my mistake.

Does anyone know if there's an easy way to undo recent actions?
There's a list with banned accounts, but as you may imagine, it's almost impossible to sort out.
If the user wants reintegration, please try to contact me.

Sorry again

Scala-Italy is just around the corner schedule up and ready.

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Ci siamo quasi, il programma e' pronto.

Almost there, the schedule is up.

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