The problem
Let X=C∖{1,−1} with basepoint 0. For a loop γ in X let w±(γ) be the degree of (γ−(±1))/∣γ−(±1)∣, the winding number of γ about ±1.
(a) Show that W:π1(X,0)→Z2, [γ]↦(w+(γ),w−(γ)), is a well-defined homomorphism.
(b) Show that W is surjective.
(c) Deduce that X is not contractible and not homotopy equivalent to S1.
Why is w+ a homomorphism π1(X,0)→Z?