Why is $\{1,2,3\} \neq \{1,2,3,\emptyset \}?$
3072
If the empty set is a subset of every set, why isn't $\{\emptyset,\{a\}\}=\{\{a\}\}$?
99480
Why is predicate "all" as in all(SET) true if the SET is empty?
103314
Let $\{K_n \}_{n \in \mathbb{N}}$ be a collection of sets, where $K_n = [n, \infty)$. Why is $\bigcap_{n \in \mathbb{N}} K_{n}$ empty?
31535
Solving an inequality : $n \geq 3$ , $n^{n} \lt (n!)^{2}$.
65379
Deriving $\neg R$ from $\{R↔(R∨(P∧¬P)), R↔¬P, ¬P→(P↔(Q→Q)), P→Q\}$
150166
What is $P([a_1,b_1]\times [a_2,b_2]\times...\times[a_k,b_k])$
58594
Is the empty set a subset of itself?
60268
$\textit{Why}$ the cases in 4 $\nmid n^2 - 3?$ (bases cases in modular induction)
78556
Why isn't [1,2,3] equal to itself in Javascript?
65549
What is the cartesian product of an empty set of sets?
51687
Is the set $ \ (\mathbb{Z}_p \setminus \mathbb{Z}) \cap \mathbb{Q}$ non-empty?
33064
Powerset of set with empty sets
96039
Why is $\frac {1\cdot2\cdot3\cdot...\cdot n}{(n+1)(n+2)...(2n)}\le \frac 1 {n+1}$
65768
What is the cardinality of the set of the empty set?
62208
If $A$ is a non-empty set, then $A \notin A$
132692
Nonempty set mapped to $\emptyset$ and vice-versa
84609
Unary intersection of the empty set