The convention for speakers to refer to themselves at the board with a single initial

Question

I found an interesting question on Math SE asked by @KCd, but it is over four years old without a clear answer. Since it seems to be more on topic here than on Math SE, I thought to post it here in case it receives good answers.

(I commented on the post a few months ago asking the OP if they would be interested in posting the question here, but since I did not receive any reply I'm making my own post; I hope there is no objection to this, but if so please let me know.)

This question is being asked on behalf of a graduate student in my department. When and where did the tradition start of a seminar or colloquium speaker using just the first initial of the speaker's last name (or initials for the speaker's first and last names) when stating a theorem due to the speaker? Attributions of results due to anyone else, including joint theorems with the speaker, are usually indicated with the other people's full last name.

Anything like a photograph of Hilbert giving a talk with "Satz (H.)" at the start of a theorem would be great to see if it exists.

Answer 1

The question probably cannot be precisely answered as stated, but there is an early example close to what you expect to see, at least in terms of time frame and the importance of the mathematician involved. It has to do with printed matter, though, not with talks, and refers to a notion, not a theorem. The notion is that of a Banach space. According to Jeff Miller, http://jeff560.tripod.com/b.html, the name originated with Maurice Fréchet (1878-1973), who in 1928 in his Les Espaces Abstraits wrote about "les espaces de M. Banach." Yet in his own book Teoria operacji liniowych, 1931, and its French version Théorie des opérations linéaires, 1932, Banach calls such spaces "the spaces of type (B)". Unfortunately the French text is not digitally available, but the Polish version can be seen here, on p. 96: http://kielich.amu.edu.pl/Stefan_Banach/pdf/teoria-operacji-pol/05.pdf It is hard to guess if Banach is following the naming convention in question, because in the initial chapters of the book he also refers to (B)-measurability, but he links this notion with the name of Baire. There is also a chapter about "spaces of type (F)".