Compact graph of a continuous map
ID: compact-graph-of-a-continuous-map
If is a compact space and is a continuous map, the graph of a function of is compact in the product topology on . Indeed,is a continuous map onto that graph, so the result follows from the continuous image of a compact space theorem. No Hausdorff assumption on is needed.
The coordinate projection map restricted to the graph is a continuous inverse to . Thus the graph is actually homeomorphic to . For instance, the graph of over has the same intrinsic topology as the interval, even though it is curved in the plane.
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