New posts in Elementary Set Theory

What does "$f: \mathbb{R} \to[0,\infty), f(x)=x^2$" mean? What is the co-domain, domain, or range?

De Morgan's formulas set theory

An explicit bijection between $\mathbb{Q}^+$ and $\mathbb{Q}$?

Is the number of primes equal to the number of integers?

What formal mathematical terms are used to talk about different scales of infinity?

Prove or disprove this set equality.

Are there more rectangles than squares?

Can an infinite set A be larger than an infinite set B but still have the same cardinality?

Doubt about Empty Set's definition as a Set.

What lies behind the definitions of split monics and epics?