Topic: Topology (Undergraduate)

The No-Retraction Theorem for the Disk

The Moore Plane Is Regular but Not Normal

The Lower Limit Topology From Half-Open Intervals

The Lower Limit Topology And Half-Open Basis Intervals

The Loop-Subdivision Proof of Van Kampen

The Long Line’s Local and Global Topology

The Long Line And Its Local Euclidean Structure

The Lexicographic Plane Is Strictly Finer Than the Product Plane

The Locally Compact Hausdorff Baire Theorem

The Klein Bottle Group from Polygon Gluing