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Topology of the unit interval

  1. Jan 30, 2013 #1
    Hi all,
    I need help with something basic but I'm not sure how to handle it. The doubt is about how to consider the topology of the unit interval I=[0,1] inherited of the real line with its usual topology (intervals of the type (a,b)).

    I think that is just to pay attention to the definition, I mean, the open subsets of 'I' would be the intersection of a usual open interval and 'I'. In this way, 'I' itself would be a open subset of the inherited topology, and all the sets of the form [0,x), (a,b) and (y,1] -with 0 < x,a,b,y <1 - would be open sets of the inherited topology.

    Please, can anyone tell me if I'm right?
    Thanks in advance.
  2. jcsd
  3. Jan 30, 2013 #2
    Sounds about right.

    Note that some sets in the subspace are open sets even if they aren't open in the larger space.

    For instance, [0, 1] is closed in R. But when we consider [0, 1] as a subspace, it's open (because the entire topological space is required to be open in any topology).

    Similarly, [0, 1), which is neither open nor closed in R is open in [0, 1].
  4. Jan 30, 2013 #3
    Thank you Tac-Tics
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