Goal:
    x : V.t  s : VSet.t  y : V.t  H0 : x = y -> False
  ============================
   ((x = y \/ VSet.In y s -> x = y \/ VSet.In y s /\ x <> y) /\
    (x = y \/ VSet.In y s /\ x <> y -> x = y \/ VSet.In y s))


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

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 3: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 3: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 3: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 3: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 3: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 3: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".
Level 2: Backtrace:

In environment
x : V.t
s : VSet.t
y : V.t
H0 : x = y -> False
Unable to unify "y" with "x".