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In a follow-up to the popular talk at CF Summit discussing how and why the Cloud Foundry team is rewriting one of the existing Cloud Foundry components, namely the DEA, in Go (codenamed “Diego” appropriately), Cloud Foundry engineer Amit Gupta shares the details of how the DEA optimizes scaling applications across your available cloud resources. In this technical post, he reviews the new auction system, and illustrates the problem Diego solves by modelling it as a mathematical optimization problem.

In Part 2, we finished defining all the formal terms and symbols you see in the StackOverflow question on the Hindley-Milner algorithm, so now we’re ready to translate what that question was asking about, namely the rules for deducing statements about type inference.

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In Part 1, we said what the building blocks of the Hindley-Milner formalization would be, and in this post we’ll thoroughly define them, and actually formulate the formalization:

Formalizing the concept of an expressionWe’ll give a recursive definition of what an expression is; in other words, we’ll state what the most basic kind of expression is, we’ll say how to create new, more complex expressions out of existing expressions, and we’ll say that only things made in this way are valid expressions.

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Mike Sierchio wrote a cool post on password strength, and the concept of entropy. As he points out, entropy isn’t always entropy. That confusion is apparently not uncommon, as it’s been asked about on IT Security Stack Exchange as well. So what’s really going on?

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I’ve been learning a bit of statistical computing with R lately on the side from Chris Paciorek’s Berkeley course. I just got introduced to knitr and it’s damned sweet! It’s an R package which takes a LaTeX file with embedded R, and produces a pure LaTeX file (similar to how Rails renders an .html.erb file into an .html file), where the resulting LaTeX file has the output of the R code.

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This question came up as a joke during a team standup a few months ago. Although the obvious answer is “no,” if you’re willing to play fast and loose with your metaphysics for a bit, the answer can be “yes” and there’s a cute solution that ties together binary numbers and binary trees.

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I was out for drinks with Josh Long and some other friends from work, when he found out I “speak math.” He had come across this StackOverflow question and asked me what it meant:

Before we figure out what it means, let’s get an idea for why we care in the first place.

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Whether you're learning math for pleasure or profit (jumping on the Big Data bandwagon), there are times when it may seem intimidating, overwhelming, confounding, etc. My assertion is that if you think like a programmer, you already have a leg up when it comes to learning math.