theorem Arroweqd (_G: wff) (_A1 _A2 _B1 _B2: set):
  $ _G -> _A1 == _A2 $ >
  $ _G -> _B1 == _B2 $ >
  $ _G -> Arrow _A1 _B1 == Arrow _A2 _B2 $;
    
      
        | Step | Hyp | Ref | Expression | 
        
          | 1 | 
           | 
          biidd | 
          _G -> (isfun f <-> isfun f)  | 
        
        
          | 2 | 
           | 
          eqsidd | 
          _G -> Dom f == Dom f  | 
        
        
          | 3 | 
           | 
          hyp _Ah | 
          _G -> _A1 == _A2  | 
        
        
          | 4 | 
          2, 3 | 
          eqseqd | 
          _G -> (Dom f == _A1 <-> Dom f == _A2)  | 
        
        
          | 5 | 
          1, 4 | 
          aneqd | 
          _G -> (isfun f /\ Dom f == _A1 <-> isfun f /\ Dom f == _A2)  | 
        
        
          | 6 | 
           | 
          eqsidd | 
          _G -> Ran f == Ran f  | 
        
        
          | 7 | 
           | 
          hyp _Bh | 
          _G -> _B1 == _B2  | 
        
        
          | 8 | 
          6, 7 | 
          sseqd | 
          _G -> (Ran f C_ _B1 <-> Ran f C_ _B2)  | 
        
        
          | 9 | 
          5, 8 | 
          aneqd | 
          _G -> (isfun f /\ Dom f == _A1 /\ Ran f C_ _B1 <-> isfun f /\ Dom f == _A2 /\ Ran f C_ _B2)  | 
        
        
          | 10 | 
          9 | 
          abeqd | 
          _G -> {f | isfun f /\ Dom f == _A1 /\ Ran f C_ _B1} == {f | isfun f /\ Dom f == _A2 /\ Ran f C_ _B2} | 
        
        
          | 11 | 
          10 | 
          conv Arrow | 
          _G -> Arrow _A1 _B1 == Arrow _A2 _B2  | 
        
      
    
    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)