Well-posedness of Einstein's Equation with Redshift Data
  We study the solvability of a system of ordinary differential equations
derived from null geodesics of the LTB metric with data given in terms of a
so-called redshift parameter. Data is introduced along these geodesics by the
luminosity distance function. We check our results with luminosity distance
depending on the cosmological constant and with the well-known FRW model.
