Bifurcation of critical points along gap-continuous families of   subspaces
  We consider the restriction of twice differentiable functionals on a Hilbert space to families of subspaces that vary continuously with respect to the gap metric. We study bifurcation of branches of critical points along these families, and apply our results to semilinear systems of ordinary differential equations. 
Anna Maria Candela and Nils Waterstraat
math.FA math.AP math.DS