Goal:
    G : t  x : V.t  i : V.t  source_vertex0 : VSet.In (s G) (V G)  H0 : x = i
  ============================
   (False \/ i = x)


DEBUG:Going to execute:
solve [ Ltac.left; t_tauto_intuit | Ltac.right; t_tauto_intuit ]
Level 3: evaluation returns
<coq-core.plugins.tauto::is_disj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := False \/ i = x
of type
constr of type tacvalue