message: Use math instead of unicode for epsilon
diff: @@ -45,7 +45,7 @@ A more general technique is to use a sparse approximation of the Rips
  introduced by Don Sheehy :cite:`sheehy13linear`. We are using the version
  described in :cite:`buchet16efficient` (except that we multiply all filtration
  values by 2, to match the usual Rips complex), which proves a
  -:math:`\frac{1+\epsilon}{1-\epsilon}`-interleaving, although in practice the
  +:math:`\frac{1+\varepsilon}{1-\varepsilon}`-interleaving, although in practice the
  error is usually smaller. A more intuitive presentation of the idea is
  available in :cite:`cavanna15geometric`, and in a video
  :cite:`cavanna15visualizing`. Passing an extra argument `sparse=0.3` at the
  