theorem takelen (l n: nat): $ len (take l n) = min (len l) n $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | lenlfn | len (lfn (\ a1, nth a1 l - 1) (min (len l) n)) = min (len l) n | 
        
          | 2 | 1 | conv take | len (take l n) = min (len l) n | 
      
    
    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
     (peano1,
      peano2,
      peano5,
      addeq,
      muleq,
      add0,
      addS,
      mul0,
      mulS)