MATH 7520: Algebraic Topology Homework

MATH 7520   Algebraic Topology

Fall 2015

Homework Problems

· Use the Universal Coefficient Theorem to determine the cohomology groups of RPn with coefficients in Z, and with coefficients in Z2.
· Use the cellular map f from RP2 to S2 which collapses the 1-cell to a point to show that the splitting in the cohomology Universal Coefficient Theorem is not natural with respect to homomorphisms induced by continuous maps.
· Compute the homology and cohomology of RP2 x RP2 with coefficients in Z, and with coefficients in Z2.
· Hatcher, page 229, problem 11
· Determine the structure of the cohomology ring H*(S1 x S1 x S1Z).
· Distinguish the spaces S2 x S4 and CP3
· If f is a map from S2n-1 to Sn and g is a map from Sn to Sn, show that the Hopf invariant of the composite g ° f is equal to the square of the degree of g times the Hopf invariant of f.
· If h is a map from S2n-1 to S2n-1 and f is a map from S2n-1 to Sn, show that the Hopf invariant of the composite f ° h is equal to the degree of h times the Hopf invariant of f.
· Identify the "orientation" double cover for a general non-orientable surface.
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Suppose p:E → M is a covering space, with E and M connected n-manifolds. If M is orientable, show that E is orientable, and that every covering transformation preserves orientation.
· Hatcher pages 257 - 259, problems 2, 5 - 9, 16, 17, 24, 25.
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Let M be a closed, connected, orientable n-manifold, and f : MM a continuous map.
If f* : Hn(M;Z) → Hn(M;Z) is an isomorphism, show that f* : Hq(M;Z) → Hq(M;Z) and f* : Hq(M;Z) → Hq(M;Z) are isomorphisms for all q.
· Hatcher, page 260, problems 28, 29, 32, 33, 34.
· For X and Y path connected, show that πn(X x Y) is isomorphic to πn(X) x πn(Y).

Dan Cohen   Fall 2015
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