New posts in Counterexamples

fiberwise-quasi-compact implies quasi-compact?

Polynomial inequality of sixth degree

Can different knots have the same numbers of quandle colorings for all quandles?

Intuition behind counterexample of Euler's sum of powers conjecture

Is a scheme Noetherian if its topological space and its stalks are?

Primality test for specific class of Proth numbers

Example of a ring with non-finitely generated unit group?

Localization and intersection

The $n$-th derivative has $n$ zeros. Can such a function be unbounded?

Can the integration of integrable sections of a measurable function of two variables ever result in a non-measurable function?