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| Mirrors > Home > MPE Home > Th. List > Mathboxes > ax-frege41 | Structured version Visualization version Unicode version | ||
Description: The affirmation of  denies the denial of
. Identical to
notnot 136. Axiom 41 of [Frege1879] p. 47. (Contributed by RP,
24-Dec-2019.) (New usage is discouraged.) |
| Ref | Expression |
|---|---|
| ax-frege41 |
     |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | wph |
. 2
 | |
| 2 | 1 | wn 3 |
. . 3
|
| 3 | 2 | wn 3 |
. 2
|
| 4 | 1, 3 | wi 4 |
1
|
| Colors of variables: wff setvar class |
| This axiom is referenced by: frege42 38140 |
| Copyright terms: Public domain | W3C validator |