The arithmetic plane
If you haven’t seen them already, you might want to read John Baez’s week205 and Lieven le Bruyn’s series of posts on the subject of spectra. I especially recommend that you take a look at the picture...
View ArticleSome quadratic reciprocity
In the previous post we showed that the splitting behavior of a rational prime in the ring of cyclotomic integers depends only on the residue class of . This is suggestive enough of quadratic...
View ArticleIdeals and the category of commutative rings
In this post I’d like to give a better (by which I mean category-theoretic) definition of the lattice of ideals than the standard one. We know that the lattice of ideals has meets and joins defined by...
View ArticleHeron’s formula
Heron’s formula for the area of a triangle with side lengths is where is the semiperimeter. Today I’d like to try to prove this using as little geometry as possible. The assumption If we assume that is...
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