If I understand it right, it’s something along the lines of: “If it’s semi-decidable, you can then treat it “as-if” decidable and move on”.
Thank you yes, that was my intuition about what it means based upon what you’d said. I couldn’t do the proof. I don’t have the patience, discipline, rigor or determination.
I suspect there’s a fiber in there someplace but that’s a guess.
wait,, no a fibration. I get the terms mixed up. It’s not my speciality.