Example of a lattice that isn't a chain?
13961
An example of a lattice that's not totally ordered
7010
Example of two non-isomorphic fields which embed inside each other
30597
Morphism that is not a mapping
35401
Examples of finite groups that are not a semidirect product
81927
Example of closed and bounded in $\mathbb Q$ set that is not compact
72875
"Naturally occurring" non-Hausdorff spaces?
15381
Indiscernible to create descending chain of elementary models
64261
example of not surjective isometry on a bounded not closed set.
38911
Squares in $\mathbb{Z}_p$ that are not squares in $\mathbb{Z}$
95481
The set of self-adjoint operators over a Hilbert space doesn't form a lattice
108408
Example of quotient mapping that is not open
114329
Example of subring that is not an ideal
41937
Can one construct a non-measurable set without Axiom of choice?
98391
example of a nonempty subset is closed under scalar multiplication but not a subspace
103460
Normal but not hermitian nor unitary
160
homeomorphism non-example
67720
Introductory text for lattice theory