Hatcher-Algebraic-Topology · Problem 3.1.2

Cohomology

Mathematics — Graph Theory · ext-multiplication-by-n

Problem

Show that the maps

G \xrightarrow{n} G

and

H \xrightarrow{n} H

multiplying each element by the integer

n

induce multiplication by

n

\mathrm{Ext}(H, G)