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Description: Lemma for bcth . Substitutions for the function F . (Contributed by Mario Carneiro, 9-Jan-2014)
| Ref | Expression | ||
|---|---|---|---|
| Hypotheses | bcth.2 | |- J = ( MetOpen ` D ) |
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| bcthlem.4 | |- ( ph -> D e. ( CMet ` X ) ) |
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| bcthlem.5 | |- F = ( k e. NN , z e. ( X X. RR+ ) |-> { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / k ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) ) ) } ) |
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| Assertion | bcthlem1 | |- ( ( ph /\ ( A e. NN /\ B e. ( X X. RR+ ) ) ) -> ( C e. ( A F B ) <-> ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | bcth.2 | |- J = ( MetOpen ` D ) |
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| 2 | bcthlem.4 | |- ( ph -> D e. ( CMet ` X ) ) |
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| 3 | bcthlem.5 | |- F = ( k e. NN , z e. ( X X. RR+ ) |-> { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / k ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) ) ) } ) |
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| 4 | opabssxp | |- { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } C_ ( X X. RR+ ) |
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| 5 | elfvdm | |- ( D e. ( CMet ` X ) -> X e. dom CMet ) |
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| 6 | 2 5 | syl | |- ( ph -> X e. dom CMet ) |
| 7 | reex | |- RR e. _V |
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| 8 | rpssre | |- RR+ C_ RR |
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| 9 | 7 8 | ssexi | |- RR+ e. _V |
| 10 | xpexg | |- ( ( X e. dom CMet /\ RR+ e. _V ) -> ( X X. RR+ ) e. _V ) |
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| 11 | 6 9 10 | sylancl | |- ( ph -> ( X X. RR+ ) e. _V ) |
| 12 | ssexg | |- ( ( { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } C_ ( X X. RR+ ) /\ ( X X. RR+ ) e. _V ) -> { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } e. _V ) |
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| 13 | 4 11 12 | sylancr | |- ( ph -> { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } e. _V ) |
| 14 | oveq2 | |- ( k = A -> ( 1 / k ) = ( 1 / A ) ) |
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| 15 | 14 | breq2d | |- ( k = A -> ( r < ( 1 / k ) <-> r < ( 1 / A ) ) ) |
| 16 | fveq2 | |- ( k = A -> ( M ` k ) = ( M ` A ) ) |
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| 17 | 16 | difeq2d | |- ( k = A -> ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) = ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) |
| 18 | 17 | sseq2d | |- ( k = A -> ( ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) <-> ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) ) |
| 19 | 15 18 | anbi12d | |- ( k = A -> ( ( r < ( 1 / k ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) ) <-> ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) ) ) |
| 20 | 19 | anbi2d | |- ( k = A -> ( ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / k ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) ) ) <-> ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) ) ) ) |
| 21 | 20 | opabbidv | |- ( k = A -> { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / k ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` k ) ) ) ) } = { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) ) } ) |
| 22 | fveq2 | |- ( z = B -> ( ( ball ` D ) ` z ) = ( ( ball ` D ) ` B ) ) |
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| 23 | 22 | difeq1d | |- ( z = B -> ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) = ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) |
| 24 | 23 | sseq2d | |- ( z = B -> ( ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) <-> ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) |
| 25 | 24 | anbi2d | |- ( z = B -> ( ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) <-> ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| 26 | 25 | anbi2d | |- ( z = B -> ( ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) ) <-> ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) ) |
| 27 | 26 | opabbidv | |- ( z = B -> { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` z ) \ ( M ` A ) ) ) ) } = { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) |
| 28 | 21 27 3 | ovmpog | |- ( ( A e. NN /\ B e. ( X X. RR+ ) /\ { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } e. _V ) -> ( A F B ) = { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) |
| 29 | 13 28 | syl3an3 | |- ( ( A e. NN /\ B e. ( X X. RR+ ) /\ ph ) -> ( A F B ) = { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) |
| 30 | 29 | 3expa | |- ( ( ( A e. NN /\ B e. ( X X. RR+ ) ) /\ ph ) -> ( A F B ) = { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) |
| 31 | 30 | ancoms | |- ( ( ph /\ ( A e. NN /\ B e. ( X X. RR+ ) ) ) -> ( A F B ) = { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) |
| 32 | 31 | eleq2d | |- ( ( ph /\ ( A e. NN /\ B e. ( X X. RR+ ) ) ) -> ( C e. ( A F B ) <-> C e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) ) |
| 33 | 4 | sseli | |- ( C e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } -> C e. ( X X. RR+ ) ) |
| 34 | simp1 | |- ( ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) -> C e. ( X X. RR+ ) ) |
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| 35 | 1st2nd2 | |- ( C e. ( X X. RR+ ) -> C = <. ( 1st ` C ) , ( 2nd ` C ) >. ) |
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| 36 | 35 | eleq1d | |- ( C e. ( X X. RR+ ) -> ( C e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } <-> <. ( 1st ` C ) , ( 2nd ` C ) >. e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } ) ) |
| 37 | fvex | |- ( 1st ` C ) e. _V |
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| 38 | fvex | |- ( 2nd ` C ) e. _V |
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| 39 | eleq1 | |- ( x = ( 1st ` C ) -> ( x e. X <-> ( 1st ` C ) e. X ) ) |
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| 40 | eleq1 | |- ( r = ( 2nd ` C ) -> ( r e. RR+ <-> ( 2nd ` C ) e. RR+ ) ) |
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| 41 | 39 40 | bi2anan9 | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( ( x e. X /\ r e. RR+ ) <-> ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) ) ) |
| 42 | simpr | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> r = ( 2nd ` C ) ) |
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| 43 | 42 | breq1d | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( r < ( 1 / A ) <-> ( 2nd ` C ) < ( 1 / A ) ) ) |
| 44 | oveq12 | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( x ( ball ` D ) r ) = ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) |
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| 45 | 44 | fveq2d | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) = ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) ) |
| 46 | 45 | sseq1d | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) <-> ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) |
| 47 | 43 46 | anbi12d | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) <-> ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| 48 | 41 47 | anbi12d | |- ( ( x = ( 1st ` C ) /\ r = ( 2nd ` C ) ) -> ( ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) <-> ( ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) ) |
| 49 | 37 38 48 | opelopaba | |- ( <. ( 1st ` C ) , ( 2nd ` C ) >. e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } <-> ( ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| 50 | 36 49 | bitrdi | |- ( C e. ( X X. RR+ ) -> ( C e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } <-> ( ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) ) |
| 51 | 35 | eleq1d | |- ( C e. ( X X. RR+ ) -> ( C e. ( X X. RR+ ) <-> <. ( 1st ` C ) , ( 2nd ` C ) >. e. ( X X. RR+ ) ) ) |
| 52 | opelxp | |- ( <. ( 1st ` C ) , ( 2nd ` C ) >. e. ( X X. RR+ ) <-> ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) ) |
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| 53 | 51 52 | bitr2di | |- ( C e. ( X X. RR+ ) -> ( ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) <-> C e. ( X X. RR+ ) ) ) |
| 54 | df-ov | |- ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) = ( ( ball ` D ) ` <. ( 1st ` C ) , ( 2nd ` C ) >. ) |
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| 55 | 35 | fveq2d | |- ( C e. ( X X. RR+ ) -> ( ( ball ` D ) ` C ) = ( ( ball ` D ) ` <. ( 1st ` C ) , ( 2nd ` C ) >. ) ) |
| 56 | 54 55 | eqtr4id | |- ( C e. ( X X. RR+ ) -> ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) = ( ( ball ` D ) ` C ) ) |
| 57 | 56 | fveq2d | |- ( C e. ( X X. RR+ ) -> ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) = ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) ) |
| 58 | 57 | sseq1d | |- ( C e. ( X X. RR+ ) -> ( ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) <-> ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) |
| 59 | 58 | anbi2d | |- ( C e. ( X X. RR+ ) -> ( ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) <-> ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| 60 | 53 59 | anbi12d | |- ( C e. ( X X. RR+ ) -> ( ( ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) <-> ( C e. ( X X. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) ) |
| 61 | 3anass | |- ( ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) <-> ( C e. ( X X. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
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| 62 | 60 61 | bitr4di | |- ( C e. ( X X. RR+ ) -> ( ( ( ( 1st ` C ) e. X /\ ( 2nd ` C ) e. RR+ ) /\ ( ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( 1st ` C ) ( ball ` D ) ( 2nd ` C ) ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) <-> ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| 63 | 50 62 | bitrd | |- ( C e. ( X X. RR+ ) -> ( C e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } <-> ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |
| 64 | 33 34 63 | pm5.21nii | |- ( C e. { <. x , r >. | ( ( x e. X /\ r e. RR+ ) /\ ( r < ( 1 / A ) /\ ( ( cls ` J ) ` ( x ( ball ` D ) r ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) } <-> ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) |
| 65 | 32 64 | bitrdi | |- ( ( ph /\ ( A e. NN /\ B e. ( X X. RR+ ) ) ) -> ( C e. ( A F B ) <-> ( C e. ( X X. RR+ ) /\ ( 2nd ` C ) < ( 1 / A ) /\ ( ( cls ` J ) ` ( ( ball ` D ) ` C ) ) C_ ( ( ( ball ` D ) ` B ) \ ( M ` A ) ) ) ) ) |