Sorry, ri is in RI. There is only one set RI.
I wish to define RI better for you. I consider it your quoted line of the proof (your one per post please).0.111... <---> { 0.1, 0.11, 0.111, ... }, where k(0.111...) = { 0.1, 0.11, 0.111, ... }
0.10101... <---> { 0.1, 0.101, 0.10101, ... }, where...