Goal:
  
  G : t
  s0 : VSet.t
  s' : VSet.t
  x : V.t
  y : V.t
  z : V.t
  d : DisjointAdd x s0 s'
  e0 : EdgeOf x y
  a : SPath s0 y z
  s1 : VSet.t
  x0 : V.t
  ============================
   (let H := CoreTactics.block in
    forall
      e : NoConfusion_SPath
            {|
              pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
              pr2 := spath_step d e0 a
            |}
            {|
              pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
              pr2 := spath_refl s1 x0
            |},
    let H0 := CoreTactics.block in
    noConfusion_SPath_obligation_2
      {|
        pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
        pr2 := spath_step d e0 a
      |}
      {|
        pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
        pr2 := spath_refl s1 x0
      |}
      (noConfusion_SPath_obligation_1
         {|
           pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
           pr2 := spath_step d e0 a
         |}
         {|
           pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
           pr2 := spath_refl s1 x0
         |} e) = e)


DEBUG:Going to execute:
change T; CoreTactics.intros_until_block
Level 5: T
 has value 
(forall
   e : NoConfusion_SPath
         {|
           pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
           pr2 := spath_step d e0 a
         |}
         {|
           pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
           pr2 := spath_refl s1 x0
         |},
 let H := CoreTactics.block in
 noConfusion_SPath_obligation_2
   {|
     pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
     pr2 := spath_step d e0 a
   |}
   {|
     pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
     pr2 := spath_refl s1 x0
   |}
   (noConfusion_SPath_obligation_1
      {|
        pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
        pr2 := spath_step d e0 a
      |}
      {|
        pr1 := {| pr1 := s1; pr2 := {| pr1 := x0; pr2 := x0 |} |};
        pr2 := spath_refl s1 x0
      |} e) = e)