My thanks to him, both for doing this interesting work in the first place, and for taking the time to let me know about errors on this page. I went to your thesis defense and took some notes. The mailing list is for the MIT Looks like you got the gist of it pretty well. The t-gates turn on before the rails on the forward inverter swing. That means the output node smoothly tracks the supply rail.
Addition is non-expanding.
You have to produce all four to stay reversible. At the end, you can uncompute A and the last carry out, so you're left with just B and Sum. That unadd path is the hard part. Very interesting stuff. My thesis will be there on Friday.