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
  idx3 : VSet.t
  idx4 : V.t
  idx2 : V.t
  b : SPath idx3 idx4 idx2
  e : NoConfusion_SPath
        {|
          pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
          pr2 := spath_step d e0 a
        |}
        {|
          pr1 := {| pr1 := idx3; pr2 := {| pr1 := idx4; pr2 := idx2 |} |};
          pr2 := b
        |}
  ============================
   (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 := idx3; pr2 := {| pr1 := idx4; pr2 := idx2 |} |};
        pr2 := b
      |}
      (noConfusion_SPath_obligation_1
         {|
           pr1 := {| pr1 := s'; pr2 := {| pr1 := x; pr2 := z |} |};
           pr2 := spath_step d e0 a
         |}
         {|
           pr1 := {| pr1 := idx3; pr2 := {| pr1 := idx4; pr2 := idx2 |} |};
           pr2 := b
         |} e) = e)


DEBUG:Going to execute:
CoreTactics.revert_until H
DEBUG LTAC Evaluated term: (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 := idx3;
                                    pr2 := {| pr1 := idx4; pr2 := idx2 |}
                                  |};
                                pr2 := b
                              |}
                              (noConfusion_SPath_obligation_1
                                 {|
                                   pr1 :=
                                     {|
                                       pr1 := s';
                                       pr2 := {| pr1 := x; pr2 := z |}
                                     |};
                                   pr2 := spath_step d e0 a
                                 |}
                                 {|
                                   pr1 :=
                                     {|
                                       pr1 := idx3;
                                       pr2 := {| pr1 := idx4; pr2 := idx2 |}
                                     |};
                                   pr2 := b
                                 |} e) = e)