| Step | Hyp | Ref | Expression | 
						
							| 1 |  | pnfxr |  |-  +oo e. RR* | 
						
							| 2 |  | icossre |  |-  ( ( A e. RR /\ +oo e. RR* ) -> ( A [,) +oo ) C_ RR ) | 
						
							| 3 | 1 2 | mpan2 |  |-  ( A e. RR -> ( A [,) +oo ) C_ RR ) | 
						
							| 4 | 3 | adantr |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( A [,) +oo ) C_ RR ) | 
						
							| 5 |  | ovolge0 |  |-  ( ( A [,) +oo ) C_ RR -> 0 <_ ( vol* ` ( A [,) +oo ) ) ) | 
						
							| 6 | 4 5 | syl |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> 0 <_ ( vol* ` ( A [,) +oo ) ) ) | 
						
							| 7 |  | mnflt0 |  |-  -oo < 0 | 
						
							| 8 |  | mnfxr |  |-  -oo e. RR* | 
						
							| 9 |  | 0xr |  |-  0 e. RR* | 
						
							| 10 |  | ovolcl |  |-  ( ( A [,) +oo ) C_ RR -> ( vol* ` ( A [,) +oo ) ) e. RR* ) | 
						
							| 11 | 3 10 | syl |  |-  ( A e. RR -> ( vol* ` ( A [,) +oo ) ) e. RR* ) | 
						
							| 12 | 11 | adantr |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,) +oo ) ) e. RR* ) | 
						
							| 13 |  | xrltletr |  |-  ( ( -oo e. RR* /\ 0 e. RR* /\ ( vol* ` ( A [,) +oo ) ) e. RR* ) -> ( ( -oo < 0 /\ 0 <_ ( vol* ` ( A [,) +oo ) ) ) -> -oo < ( vol* ` ( A [,) +oo ) ) ) ) | 
						
							| 14 | 8 9 12 13 | mp3an12i |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( -oo < 0 /\ 0 <_ ( vol* ` ( A [,) +oo ) ) ) -> -oo < ( vol* ` ( A [,) +oo ) ) ) ) | 
						
							| 15 | 7 14 | mpani |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( 0 <_ ( vol* ` ( A [,) +oo ) ) -> -oo < ( vol* ` ( A [,) +oo ) ) ) ) | 
						
							| 16 | 6 15 | mpd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> -oo < ( vol* ` ( A [,) +oo ) ) ) | 
						
							| 17 |  | simpr |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,) +oo ) ) < +oo ) | 
						
							| 18 |  | xrrebnd |  |-  ( ( vol* ` ( A [,) +oo ) ) e. RR* -> ( ( vol* ` ( A [,) +oo ) ) e. RR <-> ( -oo < ( vol* ` ( A [,) +oo ) ) /\ ( vol* ` ( A [,) +oo ) ) < +oo ) ) ) | 
						
							| 19 | 12 18 | syl |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( vol* ` ( A [,) +oo ) ) e. RR <-> ( -oo < ( vol* ` ( A [,) +oo ) ) /\ ( vol* ` ( A [,) +oo ) ) < +oo ) ) ) | 
						
							| 20 | 16 17 19 | mpbir2and |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,) +oo ) ) e. RR ) | 
						
							| 21 | 20 | ltp1d |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,) +oo ) ) < ( ( vol* ` ( A [,) +oo ) ) + 1 ) ) | 
						
							| 22 |  | peano2re |  |-  ( ( vol* ` ( A [,) +oo ) ) e. RR -> ( ( vol* ` ( A [,) +oo ) ) + 1 ) e. RR ) | 
						
							| 23 | 20 22 | syl |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( vol* ` ( A [,) +oo ) ) + 1 ) e. RR ) | 
						
							| 24 |  | simpl |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> A e. RR ) | 
						
							| 25 | 23 24 | readdcld |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) e. RR ) | 
						
							| 26 |  | 0red |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> 0 e. RR ) | 
						
							| 27 | 20 | lep1d |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,) +oo ) ) <_ ( ( vol* ` ( A [,) +oo ) ) + 1 ) ) | 
						
							| 28 | 26 20 23 6 27 | letrd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> 0 <_ ( ( vol* ` ( A [,) +oo ) ) + 1 ) ) | 
						
							| 29 | 24 23 | addge02d |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( 0 <_ ( ( vol* ` ( A [,) +oo ) ) + 1 ) <-> A <_ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) | 
						
							| 30 | 28 29 | mpbid |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> A <_ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) | 
						
							| 31 |  | ovolicc |  |-  ( ( A e. RR /\ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) e. RR /\ A <_ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) -> ( vol* ` ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) = ( ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) - A ) ) | 
						
							| 32 | 24 25 30 31 | syl3anc |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) = ( ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) - A ) ) | 
						
							| 33 | 23 | recnd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( vol* ` ( A [,) +oo ) ) + 1 ) e. CC ) | 
						
							| 34 | 24 | recnd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> A e. CC ) | 
						
							| 35 | 33 34 | pncand |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) - A ) = ( ( vol* ` ( A [,) +oo ) ) + 1 ) ) | 
						
							| 36 | 32 35 | eqtrd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) = ( ( vol* ` ( A [,) +oo ) ) + 1 ) ) | 
						
							| 37 |  | elicc2 |  |-  ( ( A e. RR /\ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) e. RR ) -> ( x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) <-> ( x e. RR /\ A <_ x /\ x <_ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) ) | 
						
							| 38 | 24 25 37 | syl2anc |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) <-> ( x e. RR /\ A <_ x /\ x <_ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) ) | 
						
							| 39 | 38 | biimpa |  |-  ( ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) /\ x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) -> ( x e. RR /\ A <_ x /\ x <_ ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) | 
						
							| 40 | 39 | simp1d |  |-  ( ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) /\ x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) -> x e. RR ) | 
						
							| 41 | 39 | simp2d |  |-  ( ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) /\ x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) -> A <_ x ) | 
						
							| 42 |  | elicopnf |  |-  ( A e. RR -> ( x e. ( A [,) +oo ) <-> ( x e. RR /\ A <_ x ) ) ) | 
						
							| 43 | 42 | ad2antrr |  |-  ( ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) /\ x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) -> ( x e. ( A [,) +oo ) <-> ( x e. RR /\ A <_ x ) ) ) | 
						
							| 44 | 40 41 43 | mpbir2and |  |-  ( ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) /\ x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) -> x e. ( A [,) +oo ) ) | 
						
							| 45 | 44 | ex |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( x e. ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) -> x e. ( A [,) +oo ) ) ) | 
						
							| 46 | 45 | ssrdv |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) C_ ( A [,) +oo ) ) | 
						
							| 47 |  | ovolss |  |-  ( ( ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) C_ ( A [,) +oo ) /\ ( A [,) +oo ) C_ RR ) -> ( vol* ` ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) <_ ( vol* ` ( A [,) +oo ) ) ) | 
						
							| 48 | 46 4 47 | syl2anc |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( vol* ` ( A [,] ( ( ( vol* ` ( A [,) +oo ) ) + 1 ) + A ) ) ) <_ ( vol* ` ( A [,) +oo ) ) ) | 
						
							| 49 | 36 48 | eqbrtrrd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> ( ( vol* ` ( A [,) +oo ) ) + 1 ) <_ ( vol* ` ( A [,) +oo ) ) ) | 
						
							| 50 | 23 20 49 | lensymd |  |-  ( ( A e. RR /\ ( vol* ` ( A [,) +oo ) ) < +oo ) -> -. ( vol* ` ( A [,) +oo ) ) < ( ( vol* ` ( A [,) +oo ) ) + 1 ) ) | 
						
							| 51 | 21 50 | pm2.65da |  |-  ( A e. RR -> -. ( vol* ` ( A [,) +oo ) ) < +oo ) | 
						
							| 52 |  | nltpnft |  |-  ( ( vol* ` ( A [,) +oo ) ) e. RR* -> ( ( vol* ` ( A [,) +oo ) ) = +oo <-> -. ( vol* ` ( A [,) +oo ) ) < +oo ) ) | 
						
							| 53 | 11 52 | syl |  |-  ( A e. RR -> ( ( vol* ` ( A [,) +oo ) ) = +oo <-> -. ( vol* ` ( A [,) +oo ) ) < +oo ) ) | 
						
							| 54 | 51 53 | mpbird |  |-  ( A e. RR -> ( vol* ` ( A [,) +oo ) ) = +oo ) |