Fiber-preserving map

A smooth map between total spaces that sends fibers to fibers over a base map.
Fiber-preserving map

Let E,M,E,ME,M,E',M' be and let π:EM\pi:E\to M and π:EM\pi':E'\to M' be . A smooth map F:EEF:E\to E' is fiber-preserving if there exists a smooth map f:MMf:M\to M' such that

πF  =  fπ. \pi'\circ F \;=\; f\circ \pi.

In this situation one says that FF covers ff, or that FF is a map over ff. If π\pi is surjective, then the base map ff is uniquely determined by FF.

When π\pi and π\pi' are surjective submersions (i.e. when they define ), a fiber-preserving smooth map is the same structure as a . A basic example is the differential dφ:TMTNd\varphi:TM\to TN associated to a smooth map φ:MN\varphi:M\to N, which is fiber-preserving between the and covers φ\varphi.

Examples

  1. Maps between products: given f:MMf:M\to M' and a smooth map g:M×FFg:M\times F\to F', the map F:M×FM×FF:M\times F\to M'\times F', F(x,u)=(f(x),g(x,u))F(x,u)=(f(x),g(x,u)), is fiber-preserving over ff.
  2. Differential of a map: for any φ:MN\varphi:M\to N, the differential dφ:TMTNd\varphi:TM\to TN satisfies τNdφ=φτM\tau_N\circ d\varphi=\varphi\circ\tau_M.
  3. Restriction to an open set: for an open inclusion i:UMi:U\hookrightarrow M, the inclusion π1(U)E\pi^{-1}(U)\hookrightarrow E is fiber-preserving over ii.