In the proof of Proposition 3A.5 in Hatcher p.265 (http://www.math.cornell.edu/~hatcher/AT/ATch3.4.pdf), at the bottow of the page, he writes,
"Since the squares commute, there is induced a map Tor(A,B) -->Tor(B,A), [...]"
How does this follow? The map Tor(A,B)-->A\otimes F_1 is the connecting...