Goal:
  
  G : t
  HI : invariants G
  HG : acyclic_no_loop G
  n : Z
  x : V.t
  y : V.t
  n0 : ~ (Some n <= lsp G x (s G))%nbar
  ============================
   (false = true <-> (Some n <= lsp G x (s G))%nbar)


DEBUG:Going to execute:
red in id
Level 2: evaluation returns
<coq-core.plugins.tauto::is_conj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := ~ (Some n <= lsp G x (s G))%nbar
of type
constr of type tacvalue

Level 2: Backtrace:

Tactic failure.
Level 2: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.
Level 1: Backtrace:

Tactic failure.