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Description: There are at least aleph-one real numbers. (Contributed by NM, 2-Feb-2005)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | aleph1re | |- ( aleph ` 1o ) ~<_ RR |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | aleph0 | |- ( aleph ` (/) ) = _om |
|
| 2 | nnenom | |- NN ~~ _om |
|
| 3 | 2 | ensymi | |- _om ~~ NN |
| 4 | 1 3 | eqbrtri | |- ( aleph ` (/) ) ~~ NN |
| 5 | ruc | |- NN ~< RR |
|
| 6 | ensdomtr | |- ( ( ( aleph ` (/) ) ~~ NN /\ NN ~< RR ) -> ( aleph ` (/) ) ~< RR ) |
|
| 7 | 4 5 6 | mp2an | |- ( aleph ` (/) ) ~< RR |
| 8 | alephnbtwn2 | |- -. ( ( aleph ` (/) ) ~< RR /\ RR ~< ( aleph ` suc (/) ) ) |
|
| 9 | 7 8 | mptnan | |- -. RR ~< ( aleph ` suc (/) ) |
| 10 | df-1o | |- 1o = suc (/) |
|
| 11 | 10 | fveq2i | |- ( aleph ` 1o ) = ( aleph ` suc (/) ) |
| 12 | 11 | breq2i | |- ( RR ~< ( aleph ` 1o ) <-> RR ~< ( aleph ` suc (/) ) ) |
| 13 | 9 12 | mtbir | |- -. RR ~< ( aleph ` 1o ) |
| 14 | fvex | |- ( aleph ` 1o ) e. _V |
|
| 15 | reex | |- RR e. _V |
|
| 16 | domtri | |- ( ( ( aleph ` 1o ) e. _V /\ RR e. _V ) -> ( ( aleph ` 1o ) ~<_ RR <-> -. RR ~< ( aleph ` 1o ) ) ) |
|
| 17 | 14 15 16 | mp2an | |- ( ( aleph ` 1o ) ~<_ RR <-> -. RR ~< ( aleph ` 1o ) ) |
| 18 | 13 17 | mpbir | |- ( aleph ` 1o ) ~<_ RR |