theorem finlamh {x: nat} (A: set x) (v: nat x):
  $ finite A -> finite ((\ x, v) |` A) $;
    
      
        | Step | Hyp | Ref | Expression | 
        
          | 1 | 
           | 
          fineq | 
          (\ x, v) |` A == (\ a1, N[a1 / x] v) |` A -> (finite ((\ x, v) |` A) <-> finite ((\ a1, N[a1 / x] v) |` A))  | 
        
        
          | 2 | 
           | 
          reseq1 | 
          \ x, v == \ a1, N[a1 / x] v -> (\ x, v) |` A == (\ a1, N[a1 / x] v) |` A  | 
        
        
          | 3 | 
           | 
          cbvlams | 
          \ x, v == \ a1, N[a1 / x] v  | 
        
        
          | 4 | 
          2, 3 | 
          ax_mp | 
          (\ x, v) |` A == (\ a1, N[a1 / x] v) |` A  | 
        
        
          | 5 | 
          1, 4 | 
          ax_mp | 
          finite ((\ x, v) |` A) <-> finite ((\ a1, N[a1 / x] v) |` A)  | 
        
        
          | 6 | 
           | 
          finlam | 
          finite A -> finite ((\ a1, N[a1 / x] v) |` A)  | 
        
        
          | 7 | 
          5, 6 | 
          sylibr | 
          finite A -> finite ((\ x, v) |` A)  | 
        
      
    
    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)