the entity using the satoshi pseudonym is one person. that is established.
Any conclusive investigations regarding if he was indeed a single entity or not?
because people have talked to him via email, on forums and IRC during 2008-2010. people have also analysed his written messages and all are saying it was one person using that pseudonym.
and yes this also means he was a sane person with no multiple personality disorders.
Correct, which indicated he most likely is/was a single person
