Assume that E and B are complex manifolds and that π : E → B is a holomorphic Serre fibration such that E admits a finite dominating family of holomorphic fiber-sprays over a small neighborhood of any point in B. We show that the parametric Oka property (POP) of B implies POP of E; conversely, POP of E implies POP of B for contractible parameter spaces. This follows from a parametric Oka principle for holomorphic liftings which we establish in the paper.Dedicated to Linda P. Rothschild
The Oka propertiesThe main result of this paper is that a subelliptic holomorphic submersion π : E → B between (reduced, paracompact) complex spaces satisfies the parametric Oka property. Subellipticity means that E admits a finite dominating family of holomorphic fiber-sprays over a neighborhood of any point in B (Def. 2.3). The conclusion means that for any Stein source space X, any compact Hausdorff space P (the parameter space), and any continuous map f : X × P → B which is X-holomorphic (i.e., such that f p = f (• , p) : X → B is holomorphic for every p ∈ P ), a continuous lifting F : X × P → E of f (satisfying π • F = f ) can be homotopically deformed through liftings of f to an X-holomorphic lifting. (See Theorem 4.2 for a precise statement.