[jderick]

Apple is pretty tight lipped about revealing the details of our work. Formal is a bit of a niche area, but you can find some info online.

Here is a course taught at UT with some slides from guest lecturers from industry that looks like a decent overview:

https://www.cerc.utexas.edu/~jaa/verification/

Also, the main conference in the area is FMCAD, you can find a lot of related work there. More recently the conference has moved more towards software, but if you look at some of the older proceedings you can find a lot of hardware related stuff.

https://www.fmcad.org/

There is decent amount of overlap between formal for hardware and software, so if you study one you will likely have enough background to get started in the other.