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Algebraic Topology
· Problem 2.2.21
Homology — Allen Hatcher
Mathematics — Topology · euler-characteristic
Problem
If a finite CW complex
X
X
X
is the union of subcomplexes
A
A
A
and
B
B
B
, show that
χ
(
X
)
=
χ
(
A
)
+
χ
(
B
)
−
χ
(
A
∩
B
)
\chi(X) = \chi(A) + \chi(B) - \chi(A \cap B)
χ
(
X
)
=
χ
(
A
)
+
χ
(
B
)
−
χ
(
A
∩
B
)
.
Related theory
Euler S Totient Function And Euler S Theorem
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