Séminaire Algèbre Géométrie Algébrique Topologie Algébrique
jeudi 22 septembre 2005 à 11:00 - salle 431
Kaoru Morisugi (Université de Wakayama)
Hopf Invariants after T. Ganea
James-Hopf invariants and Hilton-Milnor-Hopf invariants are both useful
and important in both computations and theories of homotopy groups.
Those invariants are defined on the suspension spaces.
Some people including H.Toda, T.Ganea and B.Gray, wanted to extend to more
general spaces where Hopf invariants can be defined.
On the other hand, Boardman-Steer unified these invariants after enough
suspension by taking the axiomatic approach.
I will talk about these invariants following T. Ganea's approach, and also
some interesting duality in the sense of Eckman-Hilton.
References
T. Ganea:
Generalization of homology and homotopy suspension, Comment. Math. Helv. 39 (1965).
T. Ganea: On the homotopy suspension, Comment. Math. Helv. 43 (1968).
Boardman-Steer:
On Hopf invariants, Comment. Math. Helv. 42 (1965).
B. Gray:
On the homotopy groups of mapping cones, Proc. London Math.Soc (1973).
Cornea-Lupton-Oprea-Tanea, in "Lusternik-Schnirelmann category",
Math Survey vol. 13 AMS (2003).