I wish I had taken Abstract Algebra from @mattmacauley when I was in college. Here’s how he teaches it: https://t.co/j41XzPkFOT. In contrast, when I asked my teacher what I should think about when I think about groups, he said, “Think about the axioms.” pic.twitter.com/h08gM1rGYE

— Steven Strogatz (@stevenstrogatz) January 9, 2022

Anti-calculus proposition of Erdős https://t.co/9mxBdsa0v1

— Analysis Fact (@AnalysisFact) January 12, 2022

A cross product in 7 dimensions https://t.co/Y3I6eTDXK9

— Algebra Etc. (@AlgebraFact) January 12, 2022

Leibniz’s harmonic triangle (1673). Each little threesome of unit fractions satisfies the “blue rule” below. Leibniz used this construction to calculate certain infinite sums as telescoping series. E.g., the red sum is 1/2 of the sum of reciprocal triangular numbers. pic.twitter.com/fDYO3mCLyn

— Steven Strogatz (@stevenstrogatz) January 12, 2022