Goal:
    A : Type  l : list A  n : nat
  ============================
   (skipn n (firstn (S n) l) ++ skipn (S n) l = skipn n l)


DEBUG:Going to execute:
induction l in n |- *

Goals:
    A : Type  n : nat
  ============================
   (skipn n (firstn (S n) []) ++ skipn (S n) [] = skipn n [])

  
  A : Type
  a : A
  l : list A
  n : nat
  IHl : ∀ n : nat, skipn n (firstn (S n) l) ++ skipn (S n) l = skipn n l
  ============================
   (skipn n (firstn (S n) (a :: l)) ++ skipn (S n) (a :: l) =
    skipn n (a :: l))


DEBUG:Going to execute:
simpl
DEBUG LTAC Evaluated term: l

Goals:
    A : Type  n : nat
  ============================
   (skipn n [] ++ [] = skipn n [])

  
  A : Type
  a : A
  l : list A
  n : nat
  IHl : ∀ n : nat, skipn n (firstn (S n) l) ++ skipn (S n) l = skipn n l
  ============================
   (skipn n (a :: firstn n l) ++ skipn n l = skipn n (a :: l))


DEBUG:Going to execute:
auto

Goals:
    A : Type  n : nat
  ============================
   (skipn n [] ++ [] = skipn n [])

  
  A : Type
  a : A
  l : list A
  n : nat
  IHl : ∀ n : nat, skipn n (firstn (S n) l) ++ skipn (S n) l = skipn n l
  ============================
   (skipn n (a :: firstn n l) ++ skipn n l = skipn n (a :: l))


DEBUG:Going to execute:
<coq-core.plugins.ltac::auto@0> $1 $2 $3