Set_Theory

To paraphrase Rudy Rucker:

"If the universe is science, and science is physics, and physics is mathematics, and mathematics is set theory, then EVERYTHING IS A SET."

Set theory is a branch of mathematics that is concerned with basic notions of objects belonging to sets.

Set theory provides a common foundation for many branches of mathematics. Set theory in and of itself is mostly concerned with infinite sets, and the concept of infinity.

Concepts in set theory: union, intersection, subset, complement