| Step |
Hyp |
Ref |
Expression |
| 1 |
|
recsne0.1 |
|- ( ph -> A e. No ) |
| 2 |
|
recsne0.2 |
|- ( ph -> E. x e. No ( A x.s x ) = 1s ) |
| 3 |
|
oveq2 |
|- ( x = y -> ( A x.s x ) = ( A x.s y ) ) |
| 4 |
3
|
eqeq1d |
|- ( x = y -> ( ( A x.s x ) = 1s <-> ( A x.s y ) = 1s ) ) |
| 5 |
4
|
cbvrexvw |
|- ( E. x e. No ( A x.s x ) = 1s <-> E. y e. No ( A x.s y ) = 1s ) |
| 6 |
2 5
|
sylib |
|- ( ph -> E. y e. No ( A x.s y ) = 1s ) |
| 7 |
|
simprr |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> ( A x.s y ) = 1s ) |
| 8 |
|
1sne0s |
|- 1s =/= 0s |
| 9 |
8
|
a1i |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> 1s =/= 0s ) |
| 10 |
7 9
|
eqnetrd |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> ( A x.s y ) =/= 0s ) |
| 11 |
1
|
adantr |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> A e. No ) |
| 12 |
|
simprl |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> y e. No ) |
| 13 |
11 12
|
mulsne0bd |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> ( ( A x.s y ) =/= 0s <-> ( A =/= 0s /\ y =/= 0s ) ) ) |
| 14 |
10 13
|
mpbid |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> ( A =/= 0s /\ y =/= 0s ) ) |
| 15 |
14
|
simpld |
|- ( ( ph /\ ( y e. No /\ ( A x.s y ) = 1s ) ) -> A =/= 0s ) |
| 16 |
6 15
|
rexlimddv |
|- ( ph -> A =/= 0s ) |