Goal:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  ============================
   ((e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
elim id
Level 2: evaluation returns
<coq-core.plugins.tauto::is_disj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := x = e..s \/ x = e..t
of type
constr of type tacvalue


Goals:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  ============================
   (x = e..s ->
    (e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))

  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  ============================
   (x = e..t ->
    (e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
intro
DEBUG LTAC Evaluated term: H

Goals:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  ============================
   (x = e..s ->
    (e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))

  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  ============================
   (x = e..t ->
    (e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
<coq-core.plugins.ltac::intro@0>

Goals:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  H3 : x = e..s
  ============================
   ((e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))

  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  es : list EdgeSet.elt
  H : x = e..s \/ x = e..t
  H0 : VSet.In x (V G1)
  H1 : VSet.In x (fold_right fold_fun VSet.empty es) ->
       exists e : EdgeSet.elt,
         In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  H2 : (exists e : EdgeSet.elt,
          In e es /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
       VSet.In x (fold_right fold_fun VSet.empty es)
  H3 : x = e..t
  ============================
   ((e = e \/ In e es) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
clear id