theorem sublistAteq (_n1 _n2 _L11 _L12 _L21 _L22: nat):
  $ _n1 = _n2 ->
    _L11 = _L12 ->
    _L21 = _L22 ->
    (sublistAt _n1 _L11 _L21 <-> sublistAt _n2 _L12 _L22) $;
    
      
        | Step | Hyp | Ref | Expression | 
        
          | 1 | 
           | 
          anl | 
          _n1 = _n2 /\ _L11 = _L12 -> _n1 = _n2  | 
        
        
          | 2 | 
          1 | 
          anwl | 
          _n1 = _n2 /\ _L11 = _L12 /\ _L21 = _L22 -> _n1 = _n2  | 
        
        
          | 3 | 
           | 
          anr | 
          _n1 = _n2 /\ _L11 = _L12 -> _L11 = _L12  | 
        
        
          | 4 | 
          3 | 
          anwl | 
          _n1 = _n2 /\ _L11 = _L12 /\ _L21 = _L22 -> _L11 = _L12  | 
        
        
          | 5 | 
           | 
          anr | 
          _n1 = _n2 /\ _L11 = _L12 /\ _L21 = _L22 -> _L21 = _L22  | 
        
        
          | 6 | 
          2, 4, 5 | 
          sublistAteqd | 
          _n1 = _n2 /\ _L11 = _L12 /\ _L21 = _L22 -> (sublistAt _n1 _L11 _L21 <-> sublistAt _n2 _L12 _L22)  | 
        
        
          | 7 | 
          6 | 
          exp | 
          _n1 = _n2 /\ _L11 = _L12 -> _L21 = _L22 -> (sublistAt _n1 _L11 _L21 <-> sublistAt _n2 _L12 _L22)  | 
        
        
          | 8 | 
          7 | 
          exp | 
          _n1 = _n2 -> _L11 = _L12 -> _L21 = _L22 -> (sublistAt _n1 _L11 _L21 <-> sublistAt _n2 _L12 _L22)  | 
        
      
    
    Axiom use
    axs_prop_calc
     (ax_1,
      ax_2,
      ax_3,
      ax_mp,
      itru),
    
axs_pred_calc
     (ax_gen,
      ax_4,
      ax_5,
      ax_6,
      ax_7,
      ax_10,
      ax_11,
      ax_12),
    
axs_set
     (elab,
      ax_8),
    
axs_the
     (theid,
      the0),
    
axs_peano
     (peano2,
      addeq,
      muleq)