The prover, when run on recent sage versions, failed to prove some of its
goals due to a change in sage. This commit adapts our code accordingly.
The prover passes again after this commit.
Python 3 often returns iterable map objects where Python 2 returned
list. We can just them down to lists explicitly.
Overlooked in 13c88efed0005eb6745a222963ee74564054eafb.