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Created page with "== Definition and Basic Properties == In topology, a branch of mathematics, a **closed set** is a set whose complement is an open set. More formally, a set \( C \) in a topological space \( (X, \tau) \) is closed if its complement \( X \setminus C \) is an element of the topology \( \tau \). This definition is fundamental to understanding various topological concepts and structures. Closed sets have several important properties: * The union of a finite number of cl..."
