| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 1xr |  |-  1 e. RR* | 
						
							| 2 |  | pnfxr |  |-  +oo e. RR* | 
						
							| 3 |  | 1rp |  |-  1 e. RR+ | 
						
							| 4 |  | pnfinf |  |-  ( 1 e. RR+ -> 1 ( <<< ` RR*s ) +oo ) | 
						
							| 5 | 3 4 | ax-mp |  |-  1 ( <<< ` RR*s ) +oo | 
						
							| 6 |  | breq1 |  |-  ( x = 1 -> ( x ( <<< ` RR*s ) y <-> 1 ( <<< ` RR*s ) y ) ) | 
						
							| 7 |  | breq2 |  |-  ( y = +oo -> ( 1 ( <<< ` RR*s ) y <-> 1 ( <<< ` RR*s ) +oo ) ) | 
						
							| 8 | 6 7 | rspc2ev |  |-  ( ( 1 e. RR* /\ +oo e. RR* /\ 1 ( <<< ` RR*s ) +oo ) -> E. x e. RR* E. y e. RR* x ( <<< ` RR*s ) y ) | 
						
							| 9 | 1 2 5 8 | mp3an |  |-  E. x e. RR* E. y e. RR* x ( <<< ` RR*s ) y | 
						
							| 10 |  | rexnal |  |-  ( E. x e. RR* -. A. y e. RR* -. x ( <<< ` RR*s ) y <-> -. A. x e. RR* A. y e. RR* -. x ( <<< ` RR*s ) y ) | 
						
							| 11 |  | dfrex2 |  |-  ( E. y e. RR* x ( <<< ` RR*s ) y <-> -. A. y e. RR* -. x ( <<< ` RR*s ) y ) | 
						
							| 12 | 11 | rexbii |  |-  ( E. x e. RR* E. y e. RR* x ( <<< ` RR*s ) y <-> E. x e. RR* -. A. y e. RR* -. x ( <<< ` RR*s ) y ) | 
						
							| 13 |  | xrsex |  |-  RR*s e. _V | 
						
							| 14 |  | xrsbas |  |-  RR* = ( Base ` RR*s ) | 
						
							| 15 |  | xrs0 |  |-  0 = ( 0g ` RR*s ) | 
						
							| 16 |  | eqid |  |-  ( <<< ` RR*s ) = ( <<< ` RR*s ) | 
						
							| 17 | 14 15 16 | isarchi |  |-  ( RR*s e. _V -> ( RR*s e. Archi <-> A. x e. RR* A. y e. RR* -. x ( <<< ` RR*s ) y ) ) | 
						
							| 18 | 13 17 | ax-mp |  |-  ( RR*s e. Archi <-> A. x e. RR* A. y e. RR* -. x ( <<< ` RR*s ) y ) | 
						
							| 19 | 18 | notbii |  |-  ( -. RR*s e. Archi <-> -. A. x e. RR* A. y e. RR* -. x ( <<< ` RR*s ) y ) | 
						
							| 20 | 10 12 19 | 3bitr4i |  |-  ( E. x e. RR* E. y e. RR* x ( <<< ` RR*s ) y <-> -. RR*s e. Archi ) | 
						
							| 21 | 9 20 | mpbi |  |-  -. RR*s e. Archi |