Description: A disjunction is equivalent to a threefold disjunction with single falsehood of a conjunction. (Contributed by Alexander van der Vekens, 8-Sep-2017)
Ref | Expression | ||
---|---|---|---|
Hypothesis | 3biorfd.1 | |
|
Assertion | 3bior1fand | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 3biorfd.1 | |
|
2 | 1 | intnanrd | |
3 | 2 | 3bior1fd | |