[FOM] Three Questions concerning PRA

[Rex Butler]

A few questions:

1.  What are the standard references on PRA?  Any pointers to relevant 
resources would be appreciated.

2.  Also, has computability theory been studied in the context of PRA?  For 
example, a two variable primtive recursive function f(x,y) gives a class of 
recursively enumerable sets via the image of f(n,y) as n varies.  How much 
can be done in this weak context?

3.  Finally:  it seems PRA is relatively neglected in treatments of 
mathematical logic, especially considering PRA's importance to Hilbert's 
program, etc...  Why is this so?

Rex Butler