Defining Topological Spaces help

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SUMMARY

The discussion focuses on determining whether specific collections of subsets of the real numbers ℝ define a topology. The collections under consideration include the empty set and subsets containing the closed interval [0,1], ℝ and all subsets of [0,1], and a collection defined by specific inclusion criteria regarding [0,1]. To qualify as a topology, a collection must include ℝ, the empty set, unions of subsets, and finite intersections. The participants also explore whether the resulting topology is connected and Hausdorff.

PREREQUISITES
  • Understanding of topology concepts, specifically the definition of a topology.
  • Familiarity with the properties of connected and Hausdorff spaces.
  • Knowledge of subsets and intervals in real analysis.
  • Basic set theory, including unions and intersections of sets.
NEXT STEPS
  • Study the definition and examples of topological spaces in detail.
  • Learn about connectedness and Hausdorff properties in topology.
  • Explore the concept of open and closed sets in various topologies.
  • Investigate the implications of different collections of subsets on the structure of topologies.
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Students and educators in mathematics, particularly those studying topology, as well as anyone interested in the foundational concepts of set theory and real analysis.

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Homework Statement



Let ℝ be set of real numbers. Which of the following collection of subsets of ℝ defines a topology in ℝ.

a) The empty set and all sets which contain closed interval [0,1] as a subset.

b)R and all subsets of closed interval [0,1].

c)The empty set, ℝ and all sets such that A not subset of [0,1] and [0,1] not subset of A.

Determine if obtained topology is connected and Hausdorff.

The Attempt at a Solution



Im not sure how to interpret subsets of the closed interval [0,1] and this doesn't seem like it would be an open set.
 
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"subset of [0, 1]" means exactly what it says- things like [1/2, 3/4], (1/3, 4/5), etc. This question does not ask it they are "open sets" in terms of the "usual topology", it asks whether the collection of all sets forms a topology.

You should recall that to be a "topology" a collection of subsets of set X must
1) contain X itself.
2) contain the empty set
3) contain the union of any sub-collection of these sets
4) contain the intersection of any finite sub-colection of these sets
 

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