

Tricki, a repository of mathematical know-how - jonnybgood
http://www.tricki.org

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rtpg
I've started contributing recently to proofwiki
([https://proofwiki.org/wiki/Main_Page](https://proofwiki.org/wiki/Main_Page))
which is a similar sort of collection (this one is strictly proofs though).

I think there's a pretty big fascination among mathematicians to collect and
organize the universe of information. It's always fun to think of mapping
dependencies between all known proofs

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EdwardCoffin
Timothy Gowers wrote _Is the Tricki dead?_ back in 2010 [1]. In it he
effectively said that Mathoverflow emerged after he started it, and _it_ seems
to be better at some of the types of things the Tricki was meant for. He also
talks about the fact that articles on the Tricki are harder to write, and
involve more effort.

[1] [https://gowers.wordpress.com/2010/09/24/is-the-tricki-
dead/](https://gowers.wordpress.com/2010/09/24/is-the-tricki-dead/)

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thameera
For anyone looking for a good resource for improving their mathematical
problem solving (especially for the Olympiad level), I highly recommend the
Art of Problem Solving wiki. [1]

That homepage isn't very informative, but you can search for any topic and
find explanations and problems that can be solved from that. For example:
radical axis [2]

If you're looking for a book, The Art and Craft of Problem Solving by Paul
Zeitz is the most recommended.

[1]
[http://www.artofproblemsolving.com/wiki/index.php/Main_Page](http://www.artofproblemsolving.com/wiki/index.php/Main_Page)

[2]
[http://www.artofproblemsolving.com/wiki/index.php/Radical_ax...](http://www.artofproblemsolving.com/wiki/index.php/Radical_axis)

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fantispug
This is interesting, but unfortunately the community looks stagnant; there
have only been 5 edits and 1 new article in the last year (excluding the 2
edits I just made).

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pkelchte
Always wanted to see something like this! Hope it'll get referenced a lot on
resources like Mathworld or Wikipedia. Love the extensiveness!

Dumb question maybe, but is knowledge like this often used in symbolic solver
software? If so, would it be useful to implement examples in a programming
language like Gerald Sussman did in Structure and Interpretation of Classical
Mechanics?

~~~
alexbock
I've been working on a symbolic solver lately and have had to implement a lot
of techniques manually. I'm not aware of any machine-readable database of
solving techniques (which would be great for this, especially for integrals,
because right now my code doesn't know any integration techniques that I don't
know myself).

A lot of big solvers use algorithms[0] that can't always be reduced into a
reasonable series of steps for producing nice step-by-step output, which is
why e.g. Wolfram Alpha will occasionally manage to symbolically integrate
something but tells you that a step-by-step solution is unavailable. (This
happens even with plain algebra; Wolfram Alpha can explain how to derive the
quadratic equation but not the cubic.)

Could you elaborate more on the nature of the examples from this book for
those of us who haven't read it?

[0] Risch algorithm, Gaussian elimination, etc.

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liadmat
I always thought it would be nice to have a GitHub-like thing for formal
proofs. Where anyone can define a theory using a set of axioms, and everyone
else can build theorems on top of it (and on top of existing theorems), with a
series of formal steps that are verified by the system.

~~~
JadeNB
Cameron Freer started something like this, but I think it stagnated:
[http://vdash.org](http://vdash.org) . Tom Hales put a lot of his formal proof
work on Google Code:
[https://code.google.com/p/flyspeck](https://code.google.com/p/flyspeck) . I
don't know if he has any plans to migrate to GitHub, though.

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nilkn
I believe this was started originally by Terence Tao and maybe Timothy Gowers,
though I don't think it's actively maintained anymore.

~~~
JadeNB
As EdwardCoffin mentions above
([https://news.ycombinator.com/item?id=9892043](https://news.ycombinator.com/item?id=9892043)),
Gowers says at [https://gowers.wordpress.com/2010/09/24/is-the-tricki-
dead](https://gowers.wordpress.com/2010/09/24/is-the-tricki-dead) that it was
started by Frolkin, Sisask
([https://people.kth.se/~sisask](https://people.kth.se/~sisask)), and him.

