  We propose a procedure to clarify part of the physical sector in the five
dimensional bubble geometries based on ideas similar to the split attractor
flow conjecture proposed by Denef. This procedure involves building some simple
tree-like graphs that we call skeletons without referring to the moduli space.
The skeleton (tree) exists if and only if it passes the existence conditions
which are purely based on some local CTC's (closed timelike curves) checking.
Then, we propose the conjecture similar to Denef's version which states that
every existing skeleton (tree) should correspond to some solution in which the
global absence of CTC's is ensured. Furthermore, we propose two pictures to
identify this correspondence explicitly and use some numerical examples to show
how this procedure works. We also analyze the physical sector of the simplest
bubbled supertube and see how the existence conditions constrain the charge
parameter space.
