Spec A is an affine scheme and x is a prime ideal p of A . Any presite C of spots is locally effective, but not effective unless C is empty, because the empty subset of any spot is not effective. RPot , LPot and GPot are locally effective. A morphism in Top is a local isomorphism if and only if it is a local homeomorphism. Y is a local isomorphism.
Local isomorphism is stable under base extension.