set system
(non-indexed) set whose all elements are subsets of another common set
power set
mathematical set containing all subsets of a given set
pi-system
family of sets closed under intersection
field of sets
mathematical structure of sets in an abstract space
ring of sets
Set closed under union and intersection
Steiner system
A type of block design, specifically a t-design with λ = 1 and t ≥ 2.
cover
family of subsets of a set whose union equals the whole set
partition of a set
mathematical ways to group elements of a set
sunflower
collection of sets in which every two sets have the same intersection
base
collection of open sets that is sufficient for defining a topology
subbase
Collection of subsets whose closure by finite intersections form the base of a topology
sigma-ring
Family closed under countable unions and relative complements
topology
(structure) collection of open subsets of a topological space