How many subsets of size $n$ of $S$ are required such that each element is in one subset with each other element of $S$
135743
Collection of subset generating every pairs of elements
122271
A subset of a transitive set is transitive
10472
Is every set a subset?
32754
Each number in a subset $S\subseteq \{1,\ldots,2n\}$ does not divide another one. Then $\max |S|$?
80180
Discrete and compact subset must be finite
142886
Find set with maximal cardinality given constraints
106397
Counting ways to partition a set into fixed number of subsets
146664
The union of two linearly independent subsets
150430
Let $S={1, 2, 3, 4, ....., 2070}$ find the number of subsets of $S$ whose sum of elements in $S$ is divisible by 9
2900
How many $3$-subsets of $\{1,2,\ldots,10\}$ contain at least one even and one odd integer?
31969
Partition of N into infinite number of infinite disjoint sets?
43979
The total number of subsets is $2^n$ for $n$ elements
153072
Guessing a subset of $\{1,...,N\}$
117862
Number of partitions of an $n$-element set into $k$ classes
12436
The cardinality of the set of all finite subsets of an infinite set
100061
The Maximum possible order for an element $S_n$
76381
Plain integer partitions of $n$ using $r$ parts