theorem slameqd (_G: wff) {x: nat} (_A1 _A2: set x):
  $ _G -> _A1 == _A2 $ >
  $ _G -> (\\ x, _A1) == (\\ x, _A2) $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | eqidd | _G -> snd p, y = snd p, y | 
        
          | 2 |  | eqidd | _G -> fst p = fst p | 
        
          | 3 |  | hyp _Ah | _G -> _A1 == _A2 | 
        
          | 4 | 2, 3 | sbseqd | _G -> S[fst p / x] _A1 == S[fst p / x] _A2 | 
        
          | 5 | 1, 4 | eleqd | _G -> (snd p, y e. S[fst p / x] _A1 <-> snd p, y e. S[fst p / x] _A2) | 
        
          | 6 | 5 | abeqd | _G -> {y | snd p, y e. S[fst p / x] _A1} == {y | snd p, y e. S[fst p / x] _A2} | 
        
          | 7 | 6 | sabeqd | _G -> S\ p, {y | snd p, y e. S[fst p / x] _A1} == S\ p, {y | snd p, y e. S[fst p / x] _A2} | 
        
          | 8 | 7 | conv slam | _G -> (\\ x, _A1) == (\\ x, _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)