Metamath Proof Explorer
Description: If X is a surreal sign, then it is not null. (Contributed by Scott
Fenton, 3-Aug-2011)
|
|
Ref |
Expression |
|
Hypothesis |
nosgnn0i.1 |
|
|
Assertion |
nosgnn0i |
|
Proof
Step |
Hyp |
Ref |
Expression |
1 |
|
nosgnn0i.1 |
|
2 |
|
nosgnn0 |
|
3 |
|
eleq1 |
|
4 |
1 3
|
mpbiri |
|
5 |
2 4
|
mto |
|
6 |
5
|
neir |
|