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Jan 1, 2023 at 13:23 history edited Martin Sleziak CC BY-SA 4.0
http -> https
Dec 31, 2022 at 1:22 comment added G. Blaickner Indeed, that was also what I was wondering. It seems to me that this product in this context has to be known for a much longer time. For example, Kühnel mentions in his book on differential geometry that the Kulkarni-Nomizu product was known as "double transvection" in Ricci calculus. So, this is how I got curious in how this product came to the name "Kulkarni-Nomizu" in the first place. The name seems to be already in use for quite some time. For example, Besse already used it in his book on Einstein manifolds from the 80s.
Dec 30, 2022 at 23:01 comment added Deane Yang I confess to being a little puzzled why this product wasn't already well known before all this. For one thing, it's the linearization of the Gauss equations $$ R(X,Y,Z,W) = A(X,Z)A(Y,W) - A(X,W)A(Y,Z), $$ where $A$ is the second fundamental form of a hypersurface in Euclidean space. It also appears in formula for the Riemann curvature tensor in terms of the metric.
Dec 30, 2022 at 20:51 history edited LSpice CC BY-SA 4.0
Re-edited in links (see https://mathoverflow.net/questions/437531/etymology-kulkarni-nomizu-product/437537?noredirect=1#comment1127924_437537 and https://mathoverflow.net/questions/437531/etymology-kulkarni-nomizu-product/437537?noredirect=1#comment1127925_437537)
Dec 30, 2022 at 20:37 history edited LSpice CC BY-SA 4.0
Oops, missed a typo
Dec 30, 2022 at 20:29 vote accept G. Blaickner
Dec 30, 2022 at 20:23 history edited MyShepherd CC BY-SA 4.0
added 67 characters in body
Dec 30, 2022 at 20:22 history edited LSpice CC BY-SA 4.0
Typos; link to Calabi's paper
Dec 30, 2022 at 20:18 history edited MyShepherd CC BY-SA 4.0
added 293 characters in body
Dec 30, 2022 at 20:12 history answered MyShepherd CC BY-SA 4.0