Graham reportedly died yesterday, Monday, July 6, 2020.
His AMS obituary says “he created the Erdős number.”
See also the tag in the previous post.
(That tag was created and added to several posts
just before I saw the above news of Graham’s death.
The tag, Erdős number, was suggested by an earlier post from
June 30 — the cartoonist’s death date in today’s 8:45 PM post.)