Polyhedra Module
================

.. py:class:: Polyhedron

    Polyhedron class allows users to build and inspect polyherons.  The following methods provide the properties of a polyhedron. 

    .. py:method:: equalities(self)
    
        Return a list of the equalities in a polyhedron.
        
    .. py:method:: inequalities(self)
    
        Return a list of the inequalities in a polyhedron.

    .. py:method:: constraints(self)
    
        Return ta list of the constraints of a polyhedron.

    The following unary operations can be used to inspect a polyhedron.
    
    .. py:method:: disjoint(self)
    
        Returns a polyhedron as a disjoint.
               
    .. py:method:: isuniverse(self)
    
        Return ``True`` if a polyhedron is the Universe set.    

    .. py:method:: subs(self, symbol, expression=None)
    
        Subsitutes an expression into a polyhedron and returns the result.      

To create a polyhedron, the user must use the folloing functions to define  equalities and inequalities as the contraints.
   
.. py:function:: Eq(left, right)
   
   Create a constraint by setting *left* equal to *right*.         
        
.. py:function:: Ne(left, right)

    Create a constraint by setting *left* not equal to *right*.
            
.. py:function:: Lt(left, right)
    
   Create a constraint by setting *left* less than *right*. 
        
.. py:function:: Le(left, right)
    
   Create a constraint by setting *left* less than or equal to *right*.     
        
.. py:function:: Gt(left, right)
    
   Create a constraint by setting *left* greater than *right*.        

.. py:function:: Ge(left, right)
    
   Create a constraint by setting *left* greater than or equal to *right*.