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Mirrors > Home > ILE Home > Th. List > ax-2 | Unicode version |
Description: Axiom Frege. Axiom A2 of [Margaris] p. 49. This axiom "distributes" an antecedent over two consequents. This axiom was part of Frege's original system and is known as Frege in the literature. It is also proved as Theorem *2.77 of [WhiteheadRussell] p. 108. The other direction of this axiom also turns out to be true, as demonstrated by pm5.41 240. (Contributed by NM, 5-Aug-1993.) |
Ref | Expression |
---|---|
ax-2 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | wph | . . 3 | |
2 | wps | . . . 4 | |
3 | wch | . . . 4 | |
4 | 2, 3 | wi 4 | . . 3 |
5 | 1, 4 | wi 4 | . 2 |
6 | 1, 2 | wi 4 | . . 3 |
7 | 1, 3 | wi 4 | . . 3 |
8 | 6, 7 | wi 4 | . 2 |
9 | 5, 8 | wi 4 | 1 |
Colors of variables: wff set class |
This axiom is referenced by: a2i 11 idALT 20 a2d 23 imdi 239 sbi1v 1771 ralim 2380 |
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