Almost Dedekind (not Noetherian)
67699
Integral domain that is integrally closed, one-dimensional and not noetherian
17859
Showing $F[x,y]/(ax^2+by^2-1)$ is a Dedekind domain
94413
Proving Dedekind finite implies finite assuming countable choice
96892
Number of Non-isomorphic models of Set Theory
143051
Inverting noninvertible elements in a bigger ring.
28452
Statement that is provable in $ZFC+CH$ yet unprovable in $ZFC+\lnot CH$
111689
Surjective, but not injective endomorphism
3902
Does $k+\aleph_0=\mathfrak{c}$ imply $k=\mathfrak{c}$ without the Axiom of Choice?
70218
Flat not projective, projective not free
81509
The cardinality of a countable union of countable sets, without the axiom of choice
86826
Almost a Vandermonde matrix
96549
Can we have a perfect field of characteristic $p$ with a non-archimedean valuation?
25887
Definition of Dedekind-infinity: Bijection or Injections?
90826
Constructing a subset not in $\mathcal{B}(\mathbb{R})$ explicitly
26805
Non-Noetherian 0-dimensional ring
113863
The non-existence of non-principal ultrafilters in ZF
111935
Irreducible but not prime