An Introduction to Instanton Knot Floer Homology
نویسنده
چکیده
Let Y be a finite CW-complex of dimension at most three and P → Y an SO(3) bundle. Associated with P are its Stiefel–Whitney classes wi(P ) ∈ H i(Y ;Z/2), i = 1, 2, 3. Only one of them, namely, w2(P ) ∈ H (Y ;Z/2), will be of importance to us, for the reason that w1(P ) = 0 since P is orientable, and w3(P ) = Sq (w2(P )) by the Wu formula. The class w2(P ) can be defined as follows. Let {Uα } be a trivializing cover for the bundle P then the gluing functions
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