Ciro Santilli $$ Sponsor Ciro $$ 中国独裁统治 China Dictatorship 新疆改造中心、六四事件、法轮功、郝海东、709大抓捕、2015巴拿马文件 邓家贵、低端人口、西藏骚乱
🔗
🔗
The size of a set.
🔗
For finite sizes, the definition is simple, and the intuitive name "size" matches well.
🔗
But for infinity, things are messier, e.g. the size of the real numbers is strictly larger than the size of the integers as shown by Cantor's diagonal argument, which is kind of what justifies a fancier word "cardinality" to distinguish it from the more normal word "size".
🔗
The key idea is to compare set sizes with bijections.
🔗
🔗

Ancestors

🔗