Paper 1, Section II, H

Metric and Topological Spaces
Part IB, 2010

Let f:XYf: X \rightarrow Y and g:YXg: Y \rightarrow X be continuous maps of topological spaces with fg=idYf \circ g=\mathrm{id}_{Y}.

(1) Suppose that (i) YY is path-connected, and (ii) for every yYy \in Y, its inverse image f1(y)f^{-1}(y) is path-connected. Prove that XX is path-connected.

(2) Prove the same statement when "path-connected" is everywhere replaced by "connected".