
Facts No One Really Checks (2012) - aburan28
https://rjlipton.wordpress.com/2012/07/25/facts-no-one-really-checks/
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llull
What a strange statement/article. I had to check all three of those as an
undergrad, associativity of matrix multiplication was definitely first year
linear algebra, and I think elliptic curve product was first year number
theory.

(and it still is, theorem 3.4 in these first year notes
[https://wwwf.imperial.ac.uk/~kb514/M1GLA.pdf](https://wwwf.imperial.ac.uk/~kb514/M1GLA.pdf))

"It is that they are felt too tedious or technical to prove in a course or
even a textbook." Was my degree unusually tedious?

~~~
dallbee
Nope, my lame state school made us check these as well.

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orm
A lot of matrix concepts sound a lot more natural to me if I first think of
what they mean in terms of vector spaces.

For example, I think one can derive associativity of matrix multiplication
less tediously from the observation that every matrix corresponds to a linear
transform from a vector space to another, multiplication corresponds to
function composition, and function composition is associative.

