Components and local (path) connectedness
[10/100%]A topological space is called locally path connected at if for each open set containing , there is a path connected open set with . It is called locally path connected if it is locally path connected at each . It is called locally connected at if, for each open set containing , there is a connected open set with . It is called locally connected if it is locally connected for each .
Show that a locally path connected space is locally connected.
Show that the topologist's sine curve (see the figure in Exercise 1.9.44) is not locally connected, where a space is locally connected at if for each open set containing , there is a connected open set with .
Show that an open set in is locally path connected, where a space is locally path connected at if for each open set containing , there is a path connected open set with .
Show that the path components of a locally path connected space are open sets, where a space is locally path connected at if for each open set containing , there is a path connected open set with .
Show that if is locally path connected and connected, then is path connected.
Modify the proof that a connected open set in is path connected.
Give an example of a path connected space which is not locally path connected.
Define an equivalence relation on by if there is a connected set containing both and . The equivalence classes are called the components of .
Verify that this is an equivalence relation.
Show that each component is connected, that any two components are equal or disjoint, and that the union of the components is .
Show that any connected subset of intersects at most one component and is a subset of that component.
Show that each path component is contained in a component, and that a component is a disjoint union of path components.
Show that a component is a closed set.
Show that a space is locally connected iff, for each open set , each component of is open in .
Show that a space is locally path connected iff, for each open set , each path component of is open in .
Prove that if an open set is path connected, then any two points in can actually be connected by a polygonal path in .
Show that a connected -manifold is path connected.
Mimic the proof that a connected open set in is path connected, or use Exercise 1.9.51.