If $A<C$ is finite must $A<B,B<C$ be finite
107207
$A\subseteq B\subseteq C$ ring extensions, $A\subseteq C$ finite/finitely-generated $\Rightarrow$ $A\subseteq B$ finite/finitely-generated?
88201
Suppose $X$ is a finite set and $f : X \to X$ is a function. Then $f$ is injective if and only if $f$ is surjective.
127656
How to prove that if $A$ is infinite and $B$ is finite, then $|A\cup B|=|A|$?
137707
How to prove that $(A\cup B) \cap C \subseteq A\cup (B\cap C)$
63535
Prove that if $A – C = B – C$ and $A\cap C = B\cap C$ then $A = B$
83714
$A \in B$ vs. $A \subset B$ for proofs
20335
If $A\subset B$ then $\bar{A}\subset \bar{B}$
4396
If $A^2\succ B^2$, then necessarily $A\succ B$
152382
Can an infinite set A be larger than an infinite set B but still have the same cardinality?
151928
How to prove that $N\setminus A$ is finite?
116527
Validating a proof for necessary and sufficient conditions on sets A & B such that $P(A) \cup P(B) = P(A\cup B)$
83996
For any two sets $A,B$ , $|A|\leq|B|$ or $|B|\leq|A|$
63267
Under what conditions on the sets $A$ and $B$ will it be true that $A\times B= B\times A$
119084
How many ordered pairs $(A,B)$ they are if $A$ and $B$ are subsets of $\{ 1,2,3,4,5 \}$ such that $A \cap B = \{1\}$?
70307
$(A\cap B)\cup C = A \cap (B\cup C)$ if and only if $C \subset A$
49143
Showing $A \subset B \iff A\cap B=A$
100844
How should I understand "$A$ unless $B$"?