Free math needs free software

>From TeXmacs philosophy page:

"As a mathematician, I am deeply convinced that only free programs are
acceptable from a scientific point of view. I see two main reasons for
this:

    * "A result computed by a 'mathematical' system, whose source code is
not public, can not be accepted as part of a mathematical proof.
    * "Just as a mathematician should be able to build theorems on top of
other theorems, it should be possible to freely modify and release
algorithms of mathematical software.