Description: Partial elimination of a triple disjunction by denial of a disjunct. (Contributed by Scott Fenton, 26-Mar-2011)
Ref | Expression | ||
---|---|---|---|
Assertion | 3orel1 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 3orass | |
|
2 | orel1 | |
|
3 | 1 2 | syl5bi | |