Degree of map

Algebraic Topology
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Papapetros Vaggelis
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Degree of map

#1

Post by Papapetros Vaggelis »

Let \(\displaystyle{p}\) be a polynomial function on \(\displaystyle{\mathbb{C}}\) which has no root on \(\displaystyle{S^{1}}\) .

Show that the number of roots of the equation \(\displaystyle{p(z)=0\,,z\in\mathbb{C}}\) with \(\displaystyle{|z|<1}\)

is the degree of the map \(\displaystyle{\bar{p}:S^{1}\longrightarrow S^{1}}\) specified by \(\displaystyle{\bar{p}(z)=\dfrac{p(z)}{|p(z)|}}\) .
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