Abstract
In this paper we study the set of comultiplications on a wedge of two spheres. We are primarily interested in the size of this set and properties of the comultiplications such as associativity and commutativity. Our methods involve Whitehead products in wedges of spheres and the Hopf-Hilton invariants. We apply our results to specific examples and determine the number of comultiplications, associative comultiplications and commutative comultiplications in these cases.
Similar content being viewed by others
References
Arkowitz M. Co-H-spaces, Handbook of Algebraic Topology. New York: North-Holland, 1995, 1143–1173
Arkowitz M, Gutierrez M. Comultiplications on free groups and wedge of circles. Trans Amer Math Soc, 1998, 350: 1663–1680
Arkowitz M, Lupton G. Rational co-H-spaces. Comment Math Helv, 1991, 66: 79–108
Arkowitz M, Lupton G. Equivalence classes of homotopy-associative comultiplications of finite complexes. J Pure Appl Algebra, 1995, 102: 109–136
Berstein I. A note on spaces with non-associative comultiplication. Math Proc Cambridge Philos Soc, 1964, 60: 353–354
Berstein I, Hilton P J. Categories and generalized Hopf invariants. Illinois J Math, 1960, 4: 437–451
Ganea T. Cogroups and suspensions. Invent Math, 1970, 9: 185–197
Golasinski M, Goncalves D L. Comultiplications of the wedge of two Moore spaces. Colloq Math, 1998, 76: 229–242
Hilton P J. On the homotopy groups of the union of spheres. J London Math Soc, 1955, 30: 154–172
Hilton P J. Homotopy Theory and Duality. New York: Gordon and Breach, 1965
Naylor C M. On the number of co-multiplications of a suspension. Illinois J Math, 1968, 12: 620–622
Spanier E. Algebraic Topology. New York: McGraw-Hill, 1966
Toda H. Composition Methods in Homotopy Groups of Spheres. Princeton: Princeton University Press, 1962
Whitehead G W. Elements of Homotopy Theory. Graduate Texts in Math 61. New York-Berlin: Springer-Verlag, 1978
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Arkowitz, M., Lee, DW. Comultiplications on a wedge of two spheres. Sci. China Math. 54, 9–22 (2011). https://doi.org/10.1007/s11425-010-4061-0
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11425-010-4061-0
Keywords
- co-H-spaces
- comultiplications
- homotopy associativity
- homotopy commutativity
- basic White-head products
- Hilton’s formula
- Hopf-Hilton invariants