Well order on $ℚ$ doubt
35972
Well ordering principle for rationals
55328
Let $σ$ be the relation on $R×R$ in which $(a,b) σ (x,y)$ if and only if $a ≤ x$ and $b ≤ y$. Prove that $σ$ is a partial order relation.
115100
Operator Ordering Ambiguities
107540
how to prove that $abc$ and $cba$ do not necessarily have the same order?
950
Doubts on the axiom of union?
30003
Proving that Order for N is Anti-symmetric
140868
Axiomatization of $\mathbb{Z}$ via well-ordering of positives.
132532
Things around $(\forall x)(\Psi \Rightarrow \Phi) \Leftrightarrow ((\exists z)\Psi) \Rightarrow \Phi)$
55978
Prove that for every countable ordinal $\alpha$, $\alpha\times[0,1)$ is order isomoprhic to $[0,1)$
131946
Order of an Element Under a Homomorphism
42314
Without appealing to choice, can we prove that if $X$ is well-orderable, then so too is $2^X$?
126633
Is a contradiction enough to prove a set equality to $\varnothing$?
63952
Disproving: If $(\Gamma\vdash(\phi\,\lor\psi))$, either $(\Gamma\vdash\phi)$ or $(\Gamma\vdash\psi)$ is true
34973
Is it true that the order of $ab$ is always equal to the order of $ba$?
138279
Multiplicative order and powers
25187
Why $∀x(P(x)→Q)$ is equivalent to $∃xP(x)→Q$
57724
How to prove boolean ordering question