Részhalmazelmélet
Részhalmazelmélet refers to the mathematical concept of subsets and their properties, a fundamental area within set theory. A subset is a set where all of its elements are also elements of another, larger set, known as the superset. For example, if set A contains the elements {1, 2} and set B contains the elements {1, 2, 3}, then A is a subset of B. The notation for this relationship is A ⊆ B.
The empty set, denoted by {} or ∅, is considered a subset of every set. Every set is also