#9670: Bring probability/random_variable.py to 100% coverage
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   Reporter:  kcrisman       |          Owner:  mvngu   
       Type:  enhancement    |         Status:  new     
   Priority:  major          |      Milestone:  sage-5.0
  Component:  documentation  |       Keywords:          
Work_issues:                 |       Upstream:  N/A     
   Reviewer:                 |         Author:          
     Merged:                 |   Dependencies:          
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Comment(by kohel):

 Strictly speaking the probability space is a pair (X,p:X->RR),
 and a random variable a function F:X->RR.  Since there was no
 suitable class of functions, the object returned by probability
 space is essentially p, on which one can ask for the domain X
 (as Python list, for lack of better datastructure of sets).
 As such the printing function can be a bit confusing, since it
 reports itself to be the probability space, but is implemented
 as the function.

 Now the probability function itself is a random variable (and
 explicitly inherits from them), so expectation is well-defined,
 as are other functions.

 To do this properly, one needs to create or identify a class of
 sets and their morphisms. Probability spaces would inherit from
 sets and random variables and the probability function from their
 morphisms.

 In order to implement non-finite discrete random variables the
 explicit sums should be replaced by closed forms, integrals or
 similar computations.

-- 
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/9670#comment:7>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica, 
and MATLAB

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