How many ordered pairs (A,B) , where A , B are subsets of {1,2,3,4,5} have: |A∩B|=1
119084
How many ordered pairs $(A,B)$ they are if $A$ and $B$ are subsets of $\{ 1,2,3,4,5 \}$ such that $A \cap B = \{1\}$?
127233
Cardinality of order types in $\mathbb{N}$
109682
Proposed proof of: If $A \subset B \subset \bar{A}$ and $A$ is connected, then $B$ is connected
136735
Why is the cardinality of set S is 3^n, where S is the collection of all ordered pairs of disjoint subset of {1,2,3,...,n} where n is non negative.
48523
Let $A$ be any uncountable set, and let $B$ be a countable subset of $A$. Prove that the cardinality of $A = A - B $
106756
Union and Intersection of Sets $A_{i}$ and $B_{j}$
134770
For sets $A,B$, $A \cap (B \setminus A) \subseteq \varnothing$
106564
Suppose $A,B,C$ are sets. Prove that $A\mathbin\triangle B\subseteq C \iff A\cup C=B\cup C$.
5118
Show that $n ≤ 100$ if $ \{A_1,A_2,... ,A_n\}$ is a set of distinct $3$-element subsets of $\{1, 2,... , 36\}$ such that...
146098
Number of nonempty subsets of a set with $n$ elements
56399
Proof for $A \cup B = B$ if and only if $A \subset B$
48502
number of ordered pairs of integers $(x,y)$ satisfying the equation
111324
Finding number of relations on a set with 3 elements
57822
Number of ways to choose two disjoint subsets of a set
107964
Simple combinatorics problem.
118239
If $A, B, C$ are sets prove that $(A\setminus B)\setminus C\subseteq A\setminus(B\setminus C)$
27273
Count the number of topological sorts for poset (A|)?