The following link is the proof of excision from Rotman's Algebraic Topology. Please see the the third line of the page 118. I am wondering why the equation is held. Note that it is composition of q Subdivisions here.
Thanks very much.
The following link is the proof of excision from Rotman's Algebraic Topology. Please see the the third line of the page 118. I am wondering why the equation is held. Note that it is composition of q Subdivisions here.
Thanks very much.