#
A rational obstruction to be a Gottlieb map

##
Toshihiro Yamaguchi

We investigate {\it Gottlieb map}s,which are maps $f:E\to B$that induce the maps betweenthe
Gottlieb groups$\pi_n (f)|_{G_n(E)}:G_n(E)\to G_n(B)$ for all $n$,from a rational homotopy theory
point of view.
We will define the obstruction group $O(f)$to be a Gottlieb map and a numerical invariant $o(f)$.
It naturally deduces a relative splittingof $E$ in certain cases.
We also illustrate several rational examples of Gottlieb maps and non-Gottlieb mapsby using
derivation arguments in Sullivan models.

Journal of Homotopy and Related Structures, Vol. 5(2010), No. 1, pp. 97-111