example of a space that is not semilocally simply connected
An example of a space that is not semilocally simply connected isthe following: Let
endowed with the subspace topology. Then has no simply connectedneighborhood![]()
. Indeed every neighborhood of contains (ever diminshing)homotopically non-trivial loops. Furthermore these loops are homotopically non-trivial even when considered as loops in .
The Hawaiian rings
It is essential in this example that is endowed with the topology![]()
induced by its inclusion in the plane. In contrast, the same set endowed withthe CW topology is just a bouquet of countably many circles and (as any CWcomplex) it is semilocaly simply connected.