Let X be a simply connected space with finite-dimensional rational homotopy groups. Let p∞ : U E → Baut 1 (X) be the universal fibration of simply connected spaces with fibre X. We give a DG Lie algebra model for the evaluation map ω : aut 1 (Baut 1 (X Q )) → Baut 1 (X Q ) expressed in terms of derivations of the relative Sullivan model of p∞. We deduce formulas for the rational Gottlieb group and for the evaluation subgroups of the classifying space Baut 1 (X Q ) as a consequence. We also prove that CP n Q cannot be realized as Baut 1 (X Q ) for n ≤ 4 and X with finite-dimensional rational homotopy groups.
Introduction.Given a simply connected CW complex X of finite type, let aut 1 (X) denote the space of self-maps of X homotopic to the identity map. The group-like space aut 1 (X) has a classifying space Baut 1 (X). The space Baut 1 (X) appears as the base space of the universal example p ∞ : U E → Baut 1 (X) of a fibration of simply connected CW complexes with fibre of the homotopy type of X [13,2,9].The classifying space Baut 1 (X) offers a computational challenge in homotopy theory. When X is a finite complex, Baut 1 (X) is of CW type (albeit, generally infinite) and satisfies the localization identity Baut 1 (X P ) ≃ Baut 1 (X) P for any collection of primes by work of May [9, 10]. In rational homotopy theory, models for Baut 1 (X Q ) are due to Sullivan,12,15]. The study of the classifying space using these models is an area of continued activity (see, e.g., [8,17,16]).We say a space X is π-finite if X is a simply connected CW complex and dim π * (X Q ) < ∞. A π-finite space X has a finitely generated Sullivan minimal model ∧ (V ; d). If X is a π-finite space then Baut 1 (X Q ) is one also (Proposition 2.3, below). Consequently, we may iterate the classifying space construction for πfinite rational spaces. Our first result here describes the passage from Baut 1 (X Q ) to aut 1 (Baut 1 (X Q )) in the setting of derivations of Sullivan models. We describe this result briefly now, with fuller definitions in Section 2. The relative Sullivan model for the universal fibration p ∞ : U E → Baut 1 (X) with fibre X a π-finite space is an inclusion of DG algebras. We write this model throughout as:2010 Mathematics Subject Classification. Primary: 55P62 55R15; Secondary: 55P10.