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ramshorns on Jan 21, 2019 | parent | context | favorite | on: Covariance and contravariance in C++

This seems pretty unrelated to the idea of covariant and contravariant four-vectors in relativity and electromagnetism. I wonder if there's some clever and insightful connection, or if it's more that the words just mean "varies together" and "varies oppositely".

hhmc on Jan 21, 2019 [–]

In this case the terminology is by way of, roughly speaking

   type theory <- domain theory <- category theory

Perhaps one can draw a link from the latter to the operators in electromagnetism.

ramshorns on Jan 21, 2019 | [–]

Cool. It looks like the one place I'd seen these terms used is a subcategory of one of a few different but related uses.

https://en.wikipedia.org/wiki/Covariance_and_contravariance

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