Continuous real maps from the initial-segment topology
ID: continuous-real-maps-from-the-initial-segment-topology
Give the topology whose nonempty open sets are and the finite initial segments. Every nonempty open set contains , so any two nonempty open sets intersect. A continuous map from this topological space into a Hausdorff space is constant: distinct image points would have disjoint open neighbourhoods, whose inverse images would be disjoint nonempty open sets. This includes continuous real-valued maps.
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