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Question

Math 6520 • Algebraic Topology

Fall 2024 • Question 2

Suppose that a complex \(X\) is the union of two subcomplexes \(A\) and \(B\) with \(A\), \(B\), and \(A \cap B\) contractible. Prove that \(X\) is contractible.

Raw LaTeX

Suppose that a complex \(X\) is the union of two subcomplexes \(A\) and \(B\) with \(A\), \(B\), and \(A \cap B\)
contractible. Prove that \(X\) is contractible.