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nomadreid
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- I was told that John von Neumann suggested the use of the lower-case dyet (D-with-stroke, crossed D) instead of the customary lower-case delta for the inexact differential.The related letter eth is used as a certain differential operator, so perhaps that is what my source meant. In any case, I have not been able to find any confirmation of a link to von Neumann. Did he ever suggest the dyet or the eth for the inexact differential or anything else? (And was the dyet ever used?)
Today the inexact differential is usually denoted with δ, but in a text by a Russian author I found a dyet (D-with stroke, crossed-D) instead:
In response to my question to the author about this deviation from normal usage, he stated that this was a suggestion from von Neumann. (Which of course does not justify its use in a modern text if it has not become standard, but that is another matter.) The closest I could find was a usage of the similar-looking eth
“The letter ð is sometimes used in mathematics and engineering textbooks as a symbol for a spin-weighted partial derivative.”
https://en.wikipedia.org/wiki/Spin-weighted_spherical_harmonics#Eth
Even if the author replaces the dyet by the eth, I am not sure that he is using it correctly, but that is not the point of my question. Historically, is there any connection between von Neumann and either the eth or the dyet?
(I apologize if this is not the right rubric -- since this is more the history of mathematics than of mathematics itself-- or whether a historical question even is allowed in this forum. If it is deleted or moved, then OK.)
In response to my question to the author about this deviation from normal usage, he stated that this was a suggestion from von Neumann. (Which of course does not justify its use in a modern text if it has not become standard, but that is another matter.) The closest I could find was a usage of the similar-looking eth
“The letter ð is sometimes used in mathematics and engineering textbooks as a symbol for a spin-weighted partial derivative.”
https://en.wikipedia.org/wiki/Spin-weighted_spherical_harmonics#Eth
Even if the author replaces the dyet by the eth, I am not sure that he is using it correctly, but that is not the point of my question. Historically, is there any connection between von Neumann and either the eth or the dyet?
(I apologize if this is not the right rubric -- since this is more the history of mathematics than of mathematics itself-- or whether a historical question even is allowed in this forum. If it is deleted or moved, then OK.)