Update: Alex Altair has now finished this tutorial!

A while ago I began writing a Solomonoff Induction tutorial, but now it's one of those Less Wrong articles I probably will never have time to write.

But, maybe a few of you can take what I've started, team up, and finish the thing. I'm basically just following along with the Solomonoff induction tutorials from Shane Legg (2008, 2004), but making them simpler and readable by a wider audience. I think this would be a valuable thing for Less Wrong to have, and one that would draw even more traffic to our community, but I don't have time to write it myself anymore!

Who wants to be a hero and finish this thing? The original markdown source is available here.

This is a tutorial for beginners. Those familiar with Solomonoff induction may prefer to read Rathmanner & Hutter (2011).

People disagree about things. Some say that vaccines cause autism; others say they don't. Some say everything is physical; others believe in a god. Some say that complicated financial derivatives are essential to a modern competitive economy; others think a nation's economy will do better without them. It's hard to know what is true.

And it's hard to know how to figure out what is true. Some think you should assume the things you are most certain about and then deduce all other beliefs from your original beliefs. Others think you should accept at face value the most intuitive explanations of your personal experience. Others think you should generally agree with the scientific consensus until it is disproven.

Wouldn't it be nice if finding out what's true was like baking a cake? What if there was a recipe for finding out what is true? All you'd have to do is follow the written instruction exactly, and after the last instruction you'd inevitably find yourself with some sweet, tasty truth!

As it turns out, there is an exact recipe for finding truth. It was discovered in the 1960s.

The problem is that you don't have time to follow the recipe. To find the truth to even a simple question using this recipe would require you to follow one step after another until long after the heat death of the universe, and you can't do that.

But we can find shortcuts. Suppose you know the exact recipe for baking a cake requires you to count out one molecule of H2O at a time until you have exactly 0.5 cups of water. If you did that, you ...

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