Goal:
  
  x : V.t
  p : VSet.t
  H : VSet.In x p -> False
  a : V.t
  H0 : x = a -> False
  H1 : VSet.In a p
  ============================
   ((x = a \/ VSet.In a p) /\ x <> a)


DEBUG:Going to execute:
<Coq.Init.Tauto.flatten_contravariant_conj> flags X1 X2 id
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 3: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 3: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 3: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 3: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 3: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 3: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".
Level 2: Backtrace:

In environment
x : V.t
p : VSet.t
H : VSet.In x p -> False
a : V.t
H0 : x = a -> False
H1 : VSet.In a p
Unable to unify "a" with "x".