Algebraic Topology · Problem 4.1.22

Homotopy Theory — Allen Hatcher

Mathematics — Topology · cw-approximation-countably-many-cells

Problem

Show that a path-connected space XX has a CW approximation with countably many cells iff πn(X)\pi_n(X) is countable for all nn. [Use the results on simplicial approximations to maps and spaces in §2.C.]

Related theory

Browse the problem library