In mathematics, a property holds almost everywhere when the exceptional set has measure zero. It is a phrase that makes room for both a general picture and the subtleties that sit outside it.
This notebook makes room for those subtleties, too: a definition worth revisiting, a proof that reveals a useful idea, a small observation that connects two subjects.
A notebook, in many forms
Some entries are complete explorations. Others are short fragments or starting points. Links between them are part of the thinking: a theorem can lead to an example, and an example to a better question.
Follow an idea
Browse by topic, search for a concept, or begin with any note and follow its related entries. “Referenced by” shows other places where the same idea appears.