theorem lfneq (_F1 _F2: set) (_n1 _n2: nat):
  $ _F1 == _F2 -> _n1 = _n2 -> lfn _F1 _n1 = lfn _F2 _n2 $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | anl | _F1 == _F2 /\ _n1 = _n2 -> _F1 == _F2 | 
        
          | 2 |  | anr | _F1 == _F2 /\ _n1 = _n2 -> _n1 = _n2 | 
        
          | 3 | 1, 2 | lfneqd | _F1 == _F2 /\ _n1 = _n2 -> lfn _F1 _n1 = lfn _F2 _n2 | 
        
          | 4 | 3 | exp | _F1 == _F2 -> _n1 = _n2 -> lfn _F1 _n1 = lfn _F2 _n2 | 
      
    
    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)