Goal:
    x : Z  y : Z  z : Z  H : (x <= y)%Z  H0 : (y <= z)%Z
  ============================
   (x <= z)%Z


DEBUG:Going to execute:
match goal with
           | |- _ -> _ => intro; t_tauto_intuit
           | |- _ => t_reduce; t_solver
           end || t_solver
Level 2: evaluation returns
<coq-core.plugins.tauto::is_disj@0>
where
tauto_flags := 
of type
tauto_flags
X1 := (x <= z)%Z
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 0: Backtrace:

Tactic failure.