theorem elall (A: set) (l x: nat): $ all A l -> x IN l -> x e. A $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | eleq1 | a1 = x -> (a1 e. lmems l <-> x e. lmems l) | 
        
          | 2 | 1 | conv lmem | a1 = x -> (a1 e. lmems l <-> x IN l) | 
        
          | 3 |  | eleq1 | a1 = x -> (a1 e. A <-> x e. A) | 
        
          | 4 | 2, 3 | imeqd | a1 = x -> (a1 e. lmems l -> a1 e. A <-> x IN l -> x e. A) | 
        
          | 5 | 4 | eale | A. a1 (a1 e. lmems l -> a1 e. A) -> x IN l -> x e. A | 
        
          | 6 | 5 | conv all, subset | all A l -> x IN l -> x e. A | 
      
    
    Axiom use
    axs_prop_calc
     (ax_1,
      ax_2,
      ax_3,
      ax_mp),
    
axs_pred_calc
     (ax_gen,
      ax_4,
      ax_5,
      ax_6,
      ax_7,
      ax_10,
      ax_12),
    
axs_set
     (ax_8)