Metamath Proof Explorer
Description: One direction of sbn , using fewer axioms. Compare 19.2 .
(Contributed by Steven Nguyen, 18-Aug-2023)
|
|
Ref |
Expression |
|
Assertion |
sbn1 |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
nsb |
|
2 |
|
fal |
|
3 |
1 2
|
mpg |
|
4 |
|
pm2.21 |
|
5 |
4
|
sb2imi |
|
6 |
3 5
|
mtoi |
|