theorem reseqd (_G: wff) (_A1 _A2 _B1 _B2: set):
  $ _G -> _A1 == _A2 $ >
  $ _G -> _B1 == _B2 $ >
  $ _G -> _A1 |` _B1 == _A2 |` _B2 $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | hyp _Ah | _G -> _A1 == _A2 | 
        
          | 2 |  | hyp _Bh | _G -> _B1 == _B2 | 
        
          | 3 |  | eqsidd | _G -> _V == _V | 
        
          | 4 | 2, 3 | xpeqd | _G -> Xp _B1 _V == Xp _B2 _V | 
        
          | 5 | 1, 4 | ineqd | _G -> _A1 i^i Xp _B1 _V == _A2 i^i Xp _B2 _V | 
        
          | 6 | 5 | conv res | _G -> _A1 |` _B1 == _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)