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Description: The powerset of a Dedekind-infinite set does not inject into its Cartesian product with itself. (Contributed by Mario Carneiro, 31-May-2015) (Proof shortened by AV, 18-Jul-2022)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | pwxpndom2 | |- ( _om ~<_ A -> -. ~P A ~<_ ( A |_| ( A X. A ) ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | pwfseq | |- ( _om ~<_ A -> -. ~P A ~<_ U_ n e. _om ( A ^m n ) ) |
|
| 2 | reldom | |- Rel ~<_ |
|
| 3 | 2 | brrelex2i | |- ( _om ~<_ A -> A e. _V ) |
| 4 | df1o2 | |- 1o = { (/) } |
|
| 5 | 4 | oveq2i | |- ( A ^m 1o ) = ( A ^m { (/) } ) |
| 6 | id | |- ( A e. _V -> A e. _V ) |
|
| 7 | 0ex | |- (/) e. _V |
|
| 8 | 7 | a1i | |- ( A e. _V -> (/) e. _V ) |
| 9 | 6 8 | mapsnend | |- ( A e. _V -> ( A ^m { (/) } ) ~~ A ) |
| 10 | 5 9 | eqbrtrid | |- ( A e. _V -> ( A ^m 1o ) ~~ A ) |
| 11 | ensym | |- ( ( A ^m 1o ) ~~ A -> A ~~ ( A ^m 1o ) ) |
|
| 12 | 3 10 11 | 3syl | |- ( _om ~<_ A -> A ~~ ( A ^m 1o ) ) |
| 13 | map2xp | |- ( A e. _V -> ( A ^m 2o ) ~~ ( A X. A ) ) |
|
| 14 | ensym | |- ( ( A ^m 2o ) ~~ ( A X. A ) -> ( A X. A ) ~~ ( A ^m 2o ) ) |
|
| 15 | 3 13 14 | 3syl | |- ( _om ~<_ A -> ( A X. A ) ~~ ( A ^m 2o ) ) |
| 16 | elmapi | |- ( x e. ( A ^m 1o ) -> x : 1o --> A ) |
|
| 17 | 16 | fdmd | |- ( x e. ( A ^m 1o ) -> dom x = 1o ) |
| 18 | 17 | adantr | |- ( ( x e. ( A ^m 1o ) /\ x e. ( A ^m 2o ) ) -> dom x = 1o ) |
| 19 | 1oex | |- 1o e. _V |
|
| 20 | 19 | sucid | |- 1o e. suc 1o |
| 21 | df-2o | |- 2o = suc 1o |
|
| 22 | 20 21 | eleqtrri | |- 1o e. 2o |
| 23 | 1on | |- 1o e. On |
|
| 24 | 23 | onirri | |- -. 1o e. 1o |
| 25 | nelneq2 | |- ( ( 1o e. 2o /\ -. 1o e. 1o ) -> -. 2o = 1o ) |
|
| 26 | 22 24 25 | mp2an | |- -. 2o = 1o |
| 27 | elmapi | |- ( x e. ( A ^m 2o ) -> x : 2o --> A ) |
|
| 28 | 27 | fdmd | |- ( x e. ( A ^m 2o ) -> dom x = 2o ) |
| 29 | 28 | adantl | |- ( ( x e. ( A ^m 1o ) /\ x e. ( A ^m 2o ) ) -> dom x = 2o ) |
| 30 | 29 | eqeq1d | |- ( ( x e. ( A ^m 1o ) /\ x e. ( A ^m 2o ) ) -> ( dom x = 1o <-> 2o = 1o ) ) |
| 31 | 26 30 | mtbiri | |- ( ( x e. ( A ^m 1o ) /\ x e. ( A ^m 2o ) ) -> -. dom x = 1o ) |
| 32 | 18 31 | pm2.65i | |- -. ( x e. ( A ^m 1o ) /\ x e. ( A ^m 2o ) ) |
| 33 | elin | |- ( x e. ( ( A ^m 1o ) i^i ( A ^m 2o ) ) <-> ( x e. ( A ^m 1o ) /\ x e. ( A ^m 2o ) ) ) |
|
| 34 | 32 33 | mtbir | |- -. x e. ( ( A ^m 1o ) i^i ( A ^m 2o ) ) |
| 35 | 34 | a1i | |- ( _om ~<_ A -> -. x e. ( ( A ^m 1o ) i^i ( A ^m 2o ) ) ) |
| 36 | 35 | eq0rdv | |- ( _om ~<_ A -> ( ( A ^m 1o ) i^i ( A ^m 2o ) ) = (/) ) |
| 37 | djuenun | |- ( ( A ~~ ( A ^m 1o ) /\ ( A X. A ) ~~ ( A ^m 2o ) /\ ( ( A ^m 1o ) i^i ( A ^m 2o ) ) = (/) ) -> ( A |_| ( A X. A ) ) ~~ ( ( A ^m 1o ) u. ( A ^m 2o ) ) ) |
|
| 38 | 12 15 36 37 | syl3anc | |- ( _om ~<_ A -> ( A |_| ( A X. A ) ) ~~ ( ( A ^m 1o ) u. ( A ^m 2o ) ) ) |
| 39 | omex | |- _om e. _V |
|
| 40 | ovex | |- ( A ^m n ) e. _V |
|
| 41 | 39 40 | iunex | |- U_ n e. _om ( A ^m n ) e. _V |
| 42 | 1onn | |- 1o e. _om |
|
| 43 | oveq2 | |- ( n = 1o -> ( A ^m n ) = ( A ^m 1o ) ) |
|
| 44 | 43 | ssiun2s | |- ( 1o e. _om -> ( A ^m 1o ) C_ U_ n e. _om ( A ^m n ) ) |
| 45 | 42 44 | ax-mp | |- ( A ^m 1o ) C_ U_ n e. _om ( A ^m n ) |
| 46 | 2onn | |- 2o e. _om |
|
| 47 | oveq2 | |- ( n = 2o -> ( A ^m n ) = ( A ^m 2o ) ) |
|
| 48 | 47 | ssiun2s | |- ( 2o e. _om -> ( A ^m 2o ) C_ U_ n e. _om ( A ^m n ) ) |
| 49 | 46 48 | ax-mp | |- ( A ^m 2o ) C_ U_ n e. _om ( A ^m n ) |
| 50 | 45 49 | unssi | |- ( ( A ^m 1o ) u. ( A ^m 2o ) ) C_ U_ n e. _om ( A ^m n ) |
| 51 | ssdomg | |- ( U_ n e. _om ( A ^m n ) e. _V -> ( ( ( A ^m 1o ) u. ( A ^m 2o ) ) C_ U_ n e. _om ( A ^m n ) -> ( ( A ^m 1o ) u. ( A ^m 2o ) ) ~<_ U_ n e. _om ( A ^m n ) ) ) |
|
| 52 | 41 50 51 | mp2 | |- ( ( A ^m 1o ) u. ( A ^m 2o ) ) ~<_ U_ n e. _om ( A ^m n ) |
| 53 | endomtr | |- ( ( ( A |_| ( A X. A ) ) ~~ ( ( A ^m 1o ) u. ( A ^m 2o ) ) /\ ( ( A ^m 1o ) u. ( A ^m 2o ) ) ~<_ U_ n e. _om ( A ^m n ) ) -> ( A |_| ( A X. A ) ) ~<_ U_ n e. _om ( A ^m n ) ) |
|
| 54 | 38 52 53 | sylancl | |- ( _om ~<_ A -> ( A |_| ( A X. A ) ) ~<_ U_ n e. _om ( A ^m n ) ) |
| 55 | domtr | |- ( ( ~P A ~<_ ( A |_| ( A X. A ) ) /\ ( A |_| ( A X. A ) ) ~<_ U_ n e. _om ( A ^m n ) ) -> ~P A ~<_ U_ n e. _om ( A ^m n ) ) |
|
| 56 | 55 | expcom | |- ( ( A |_| ( A X. A ) ) ~<_ U_ n e. _om ( A ^m n ) -> ( ~P A ~<_ ( A |_| ( A X. A ) ) -> ~P A ~<_ U_ n e. _om ( A ^m n ) ) ) |
| 57 | 54 56 | syl | |- ( _om ~<_ A -> ( ~P A ~<_ ( A |_| ( A X. A ) ) -> ~P A ~<_ U_ n e. _om ( A ^m n ) ) ) |
| 58 | 1 57 | mtod | |- ( _om ~<_ A -> -. ~P A ~<_ ( A |_| ( A X. A ) ) ) |