Description: Swap antecedents. Theorem *2.04 of WhiteheadRussell p. 100. This was the third axiom in Frege's logic system, specifically Proposition 8 of Frege1879 p. 35. Its associated inference is com12 . (Contributed by NM, 27-Dec-1992) (Proof shortened by Wolf Lammen, 12-Sep-2012)
Ref | Expression | ||
---|---|---|---|
Assertion | pm2.04 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | id | |
|
2 | 1 | com23 | |