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Cris Perdue
“No man ever steps in the same river twice, for it's not the same river and he's not the same man.” ― Heraclitus
“No man ever steps in the same river twice, for it's not the same river and he's not the same man.” ― Heraclitus


Mathtoys has just recently added support for working with sums and differences of fractions.

- If you select the sum or difference of an integer and a fraction, it will offer to convert the sum or difference to a single fraction.

- If you select a positive integer, it will offer to compute its prime factors for you. This works for all integers up to a billion, and many beyond that.

- If you select the sum or difference of two fractions and then give a desired common denominator, it will convert them to that denominator.

Mathtoys aims to keep you thinking about the math you are doing (while helping you be quicker and more reliable!). This is one reason why it doesn't simply find least common denominators for you.

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Mathtoys update
Mathtoys has evolved considerably since my last update, and the changes post frequently to the site. There has been a fundamental change in the primary approach to solving an algebra problem, which itself changes some aspects of the user experience, and a h...
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Vacuously true statements
You can think of a vacuously true statement as a sort of mathematical joke. For example, if Santa Claus does not have any pigs, it is mathematically true that “All of Santa’s pigs can fly”! Vacuously true statements can also play a role in mathematical fall...
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Thanks to Brian Lewis for his recent usability input on Mathtoys, including recent significant changes to it (announcement upcoming).

Also much-belated thanks to Terry Hayes for earlier input.

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Extended abstract titled "Creating Usable Computer Tools that Reason Mathematically", presented at the ThEdu'15 workshop, part of CICM 2015. This gives an overview of motivations and approaches taken in Mathtoys to make a usable interactive assistant for working on textbook algebra problems.

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Slides of my talk at the ThEdu'15 workshop on Theorem-proving components in education last week, part of CICM 2015.

Project home officially moved to GitHub.

Mathtoys and the Prooftoys engine that powers it are now officially moved to GitHub. The project was originally hosted on Google Code, but Google Code is shutting down, and source code management has moved from Mercurial to Git. Fortunately it was not necessary to lose any revision history, and GitHub has many great tools for anyone involved in development of a project.

Repositories on Google Code and will not receive updates to the source code in the future., and will eventually be removed.

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Happy Pi Day!

In honor of this day here is a link to an article about the wonder of mathematics in science, and physics in particular. The article is "The Unreasonable Effectiveness of Mathematics in the Natural Sciences" ( by Nobel Prize winner Eugene Wigner.

You may not want to read the entire article, so let me quote the conclusion:

"The miracle of the appropriateness of the language of mathematics for the formulation of the laws of physics is a wonderful gift which we neither understand nor deserve. We should be grateful for it and hope that it will remain valid in future research and that it will extend, for better or for worse, to our pleasure, even though perhaps also to our bafflement, to wide branches of learning."
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