Digest PJ's thesis

[ecpeterson]

PJ, a 2018 Behrens student, wrote his thesis on reproducing the A-H-S result using the Hopf ring methods of R-W-Y:

https://curate.nd.edu/show/hd76rx9419z .

Since we spend all this effort introducing Hopf ring methods in Ch 4, it would be good to digest these results and include a summary of them. Such a summary would perhaps belong at the very end of 5.5.