A subset of R^n is any collection of points of R^n. It is directly related to the general idea of subsets where A is a subset of B if and only if every element of A is also an element of B.
In formal terms:
As such, the following cases are also subsets:
- Every set is a subset of itself
- The empty set is a subset of all sets
In the second case, this is said to be vacuously true, as there’s no x to even check a property of, therefore making the statement true by default.