Effective Constructive Algebraic Topology - Institut Fourier

CW-complex:
X = lim Xn = {(D
→ n n
i , fi : S n−1 → Xn−1)1≤i≤mn }n∈N
Associated cellular chain complex:
(mn−1) dn (mn)
· · · ←− Z ←− Z ←− · · ·
Coefficient α1,1 of dn in column 1 and row 1
⇒ g n
1,1 : Sn−1 → Y n−1
1
f n
1 : Sn−1 → X n−1
obtained from g n 1,1 :
= Xn−1 /[X n−2 ∪ (∪i=1D n−1
i )] = S n−1
⇒ α1,1 = deg(g n 1,1 ).
11