theorem grecaux20 (F K: set) (k x z: nat): $ grecaux2 z K F x 0 k = z $;
    
      
        | Step | Hyp | Ref | Expression | 
|---|
        
          | 1 |  | recn0 | recn z (\\ a1, \ a2, F @ (a1, grecaux1 K x k (x - suc a1), a2)) 0 = z | 
        
          | 2 | 1 | conv grecaux2 | grecaux2 z K F x 0 k = z | 
      
    
    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),
    
axs_the
     (theid,
      the0),
    
axs_peano
     (peano1,
      peano2,
      peano5,
      addeq,
      muleq,
      add0,
      addS,
      mul0,
      mulS)