lemma.cafe is open
A small place for lemmas and coffee
In mathematics, a lemma is one of those modest results that nobody makes a fuss about, yet everybody reaches for at the crucial moment. Lemmas rarely get names, but they hold up half of every textbook.
This blog aims for something similar: small, not-too-serious pieces that are hopefully useful.1Why a cafe? Because a mathematician is a machine for turning coffee into theorems. The line is usually credited to Erdős, though it was probably Rényi. Expect calculus, analysis, complex analysis, linear algebra, probability and statistics, with the occasional detour.
Every post comes in Simplified Chinese, Traditional Chinese and English (unless I’m lazy). Use the switcher at the top right.
Grab a cup and take your time.