Consider the product of Grassmannians G:=G(a′,A∗)×G(b′,B∗)×G(c′,C∗) with three projections πi.
Let
E=E(a′,b′,c′):=⨂3i=1π∗i(Si)
be the vector bundle that is the tensor product of the pullbacks of universal subspace bundles Si.
Let P→G denote the proj…