Goal:
  
  G : t
  HI : invariants
  z : V.t
  hin : VSet.In z (V G)
  x : V.t
  y : V.t
  x0 : Z
  p : PathOf y z
  IHp : VSet.In z (V G) -> VSet.In y (V G)
  H : VSet.In (x, x0, y)..s (V G)
  H0 : VSet.In (x, x0, y)..t (V G)
  ============================
   (VSet.In x (V G))


DEBUG:Going to execute:
<coq-core.plugins.ltac::trivial@0> $1 $2

Goals:

DEBUG:Going to execute:
repeat (do_intro; try do_atom)

Goals:

DEBUG:Going to execute:
try arith_congr

Goals:

DEBUG:Going to execute:
solve [ split; do_ccl ]