释义 |
Connected SpaceA Space is connected if any two points in can be connected by a curve lying wholly within . ASpace is 0-connected (a.k.a. Pathwise-Connected) if every Map from a 0-Sphere to theSpace extends continuously to the 1-Disk. Since the 0-Sphere is the two endpoints of an interval(1-Disk), every two points have a path between them. A space is 1-connected (a.k.a. Simply Connected) ifit is 0-connected and if every Map from the 1-Sphere to it extends continuously to a Map from the2-Disk. In other words, every loop in the Space is contractible. A Space is -MultiplyConnected if it is -connected and if every Map from the -Sphere into it extends continuouslyover the -Disk.
A theorem of Whitehead says that a Space is infinitely connected Iff it is contractible. See also Connectivity, Locally Pathwise-Connected Space, Multiply Connected, Pathwise-Connected,Simply Connected
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