Goal:
    G1 : t  ext : EdgeSet.t  x : VSet.elt
  ============================
   ((exists e : EdgeSet.elt,
       EdgeSet.In e ext /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1)) ->
    exists e : EdgeSet.elt,
      In e (EdgeSet.elements ext) /\
      (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrmove@1> $1 $2

Goals:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  _a_ : In e (EdgeSet.elements ext)
  _b_ : (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  ============================
   (exists e : EdgeSet.elt,
      EdgeSet.In e ext /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))

  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  _a_ : EdgeSet.In e ext
  _b_ : (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  ============================
   (exists e : EdgeSet.elt,
      In e (EdgeSet.elements ext) /\
      (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
exists e

Goals:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  _a_ : In e (EdgeSet.elements ext)
  _b_ : (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  ============================
   (exists e : EdgeSet.elt,
      EdgeSet.In e ext /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))

  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  _a_ : EdgeSet.In e ext
  _b_ : (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  ============================
   (exists e : EdgeSet.elt,
      In e (EdgeSet.elements ext) /\
      (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


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

Goals:
  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  _a_ : In e (EdgeSet.elements ext)
  _b_ : (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  ============================
   (EdgeSet.In e ext /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))

  
  G1 : t
  ext : EdgeSet.t
  x : VSet.elt
  e : EdgeSet.elt
  _a_ : EdgeSet.In e ext
  _b_ : (x = e..s \/ x = e..t) /\ VSet.In x (V G1)
  ============================
   (In e (EdgeSet.elements ext) /\ (x = e..s \/ x = e..t) /\ VSet.In x (V G1))


DEBUG:Going to execute:
split => //
DEBUG LTAC Evaluated term: e
DEBUG LTAC Evaluated term: e