theorem rneqd (_G: wff) (_A1 _A2: set):
  $ _G -> _A1 == _A2 $ >
  $ _G -> Ran _A1 == Ran _A2 $;
    
      
        | Step | Hyp | Ref | Expression | 
        
          | 1 | 
           | 
          eqidd | 
          _G -> x, y = x, y  | 
        
        
          | 2 | 
           | 
          hyp _Ah | 
          _G -> _A1 == _A2  | 
        
        
          | 3 | 
          1, 2 | 
          eleqd | 
          _G -> (x, y e. _A1 <-> x, y e. _A2)  | 
        
        
          | 4 | 
          3 | 
          exeqd | 
          _G -> (E. x x, y e. _A1 <-> E. x x, y e. _A2)  | 
        
        
          | 5 | 
          4 | 
          abeqd | 
          _G -> {y | E. x x, y e. _A1} == {y | E. x x, y e. _A2} | 
        
        
          | 6 | 
          5 | 
          conv Ran | 
          _G -> Ran _A1 == Ran _A2  | 
        
      
    
    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)