Is this element a subset of set A?
124325
Element of, subset of and empty sets
43068
Let A and B be sets. Show that A is a subset of B if and only if for any set C, one has A union C is a subset of B union C.
148025
Is there an operator for 'contained in set or subset or subset of subset' and so on?
40232
What do we mean when we say "Let $x$ be an element of the set $\mathbb{R}$"?
70278
$A\subseteq B\to C\setminus B\subseteq C\setminus A\,$ -- how to prove this?
3072
If the empty set is a subset of every set, why isn't $\{\emptyset,\{a\}\}=\{\{a\}\}$?
146204
Subsets sharing at most $i$ elements
77791
Proving an inclusion related to algebraic sets and interpreting it
81406
Does every set have a group structure?
123498
Is "empty set" an element of a set?
63717
Is the closure of a set equal to the closure of the closure of that set?
130771
Sets and the principle of inclusion and exclusion
64519
Subsets of a list
60309
Let X be a subset of {1,2,...,2014}...
16056
Is empty set element of every set if it is subset of every set?
117561
A set is infinite iff there is a one-to-one correspondent with one of its proper subsets?
43871
Is this subset linearly independent or linearly dependent?