Proving $\text{card}(A\times A)=\text{card}(A)$ by transfinite induction?
13924
For all infinite cardinals $\kappa, \ (\kappa \times \kappa, <_{cw}) \cong (\kappa, \in).$
154133
Flawed proof by induction that $a^{n-1}=1$
89167
Cardinality of equivalence relations in $\mathbb{N}$
32950
Fake induction proofs
20346
'Algebraic' way to prove the boolean identity $a + \overline{a}*b = a + b$
83475
Prove Or Disprove: tr(AB)=tr(A)*tr(B)
58267
Godel's pairing function and proving c = c*c for aleph cardinals
142534
Proof of $k {n\choose k} = n {n-1 \choose k-1}$ using direct proof
140440
Proving $(A\times C)\cup(B\times D)\subseteq(A\cup B)\times(C\cup D)$
55273
Prove by mathematical induction that: $\forall n \in \mathbb{N}: 3^{n} > n^{3}$
67058
Prove that $\text{rank}(X^TX)=\text{rank}(X)$
62936
Proving equivalencies of two versions of the Axiom of Choice
47670
Algebraic proof of $\sum_{i=0}^k{{n \choose i}{m \choose {k-i}}}= {{m+n}\choose k}$
155897
Proof by induction - is this correct?
80916
How to prove that if $A\subseteq A\times A$, then $A=\varnothing$?
14161
Proof of when is $A=X^TX$ invertible?
28565
Prove $\operatorname{rank}A^TA=\operatorname{rank}A$ for any $A\in M_{m \times n}$