This commit introduced a new module in sympy: the refine module. The
purpose of this module is to simplify expressions when they are bound to
assumptions. For example, if you know that x>0, then you can simplify
abs(x) to x. This code was traditionally embedded into the core …

The logic module is slowly becoming useful. This week I managed to get
some basic inference in propositional logic working. This should be
enough for the assumption sysmtem (although having first-order inference
would be cool). You can pull from my branch:
`` git pull http://fa.bianp.net/git/sympy.git …

The first task for my Summer of Code project is to write a nice boolean
algebra module. I wanted a clean module that follows SymPy's object
model and that plays well with other objects. In practice this means
that it should inherit from Basic and that it should behave well …

As a prerequisite of my GSOC project I have to do some modifications on
sympy's current logic module (see previous post), so I decided to go out
and take a look at what others are doing in this area. aima-python is
a project that tries to implement all algorithms found …