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Description: The inferior limit of the empty set. (Contributed by Glauco Siliprandi, 2-Jan-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | liminf0 | |- ( liminf ` (/) ) = +oo |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nftru | |- F/ x T. |
|
| 2 | 0ex | |- (/) e. _V |
|
| 3 | 2 | a1i | |- ( T. -> (/) e. _V ) |
| 4 | 0red | |- ( T. -> 0 e. RR ) |
|
| 5 | noel | |- -. x e. (/) |
|
| 6 | elinel1 | |- ( x e. ( (/) i^i ( 0 [,) +oo ) ) -> x e. (/) ) |
|
| 7 | 6 | con3i | |- ( -. x e. (/) -> -. x e. ( (/) i^i ( 0 [,) +oo ) ) ) |
| 8 | 5 7 | ax-mp | |- -. x e. ( (/) i^i ( 0 [,) +oo ) ) |
| 9 | pm2.21 | |- ( -. x e. ( (/) i^i ( 0 [,) +oo ) ) -> ( x e. ( (/) i^i ( 0 [,) +oo ) ) -> ( (/) ` x ) e. RR* ) ) |
|
| 10 | 8 9 | ax-mp | |- ( x e. ( (/) i^i ( 0 [,) +oo ) ) -> ( (/) ` x ) e. RR* ) |
| 11 | 10 | adantl | |- ( ( T. /\ x e. ( (/) i^i ( 0 [,) +oo ) ) ) -> ( (/) ` x ) e. RR* ) |
| 12 | 1 3 4 11 | liminfval3 | |- ( T. -> ( liminf ` ( x e. (/) |-> ( (/) ` x ) ) ) = -e ( limsup ` ( x e. (/) |-> -e ( (/) ` x ) ) ) ) |
| 13 | 12 | mptru | |- ( liminf ` ( x e. (/) |-> ( (/) ` x ) ) ) = -e ( limsup ` ( x e. (/) |-> -e ( (/) ` x ) ) ) |
| 14 | mpt0 | |- ( x e. (/) |-> ( (/) ` x ) ) = (/) |
|
| 15 | 14 | fveq2i | |- ( liminf ` ( x e. (/) |-> ( (/) ` x ) ) ) = ( liminf ` (/) ) |
| 16 | mpt0 | |- ( x e. (/) |-> -e ( (/) ` x ) ) = (/) |
|
| 17 | 16 | fveq2i | |- ( limsup ` ( x e. (/) |-> -e ( (/) ` x ) ) ) = ( limsup ` (/) ) |
| 18 | limsup0 | |- ( limsup ` (/) ) = -oo |
|
| 19 | 17 18 | eqtri | |- ( limsup ` ( x e. (/) |-> -e ( (/) ` x ) ) ) = -oo |
| 20 | 19 | xnegeqi | |- -e ( limsup ` ( x e. (/) |-> -e ( (/) ` x ) ) ) = -e -oo |
| 21 | xnegmnf | |- -e -oo = +oo |
|
| 22 | 20 21 | eqtri | |- -e ( limsup ` ( x e. (/) |-> -e ( (/) ` x ) ) ) = +oo |
| 23 | 13 15 22 | 3eqtr3i | |- ( liminf ` (/) ) = +oo |