At one point I had copies of the handwritten notes Leo created about the McLaughlin conjecture and I know a similar set of notes exist titled Arithmetically incomparable arithmetic singletons. I've since lost track of these and need to consult them and Leo doesn't seem to have easy access to them anymore.
I'd like to consult these notes and I've also agreed to finish writing up the results from them that go beyond what Simpson covers in his paper: implicitly definability in arithmetic (I started after grad school but stopped while I left to program). Also, if I get copies, I'll make sure they get uploaded somewhere everyone can access (after I double check with Leo).
Or, you could just link/attach below and it's automatic since I'm sure he's find with that.
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If Leo doesn't want to bother uploading to arxiv himself (no option to upload for others even with permission) I think computability.org will host once they finish their remodel (agreed to do so for a thesis in a similar situation)..