I wonder if that Kolmogorov essay on the equal sign might not rather be Frege's Begriffsschrift (the Wikipedia page links to a facsimile version: https://en.m.w

I wonder if that Kolmogorov essay on the equal sign might not rather be Frege's Begriffsschrift (the Wikipedia page links to a facsimile version: https://en.m.wikipedia.org/wiki/Begriffsschrift https://en.m.wikipedia.org/wiki/Begriffsschrift).