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| Mirrors > Home > ILE Home > Th. List > notbid | Unicode version | ||
| Description: Equivalence property for negation. Deduction form. (Contributed by NM, 21-May-1994.) (Revised by Mario Carneiro, 31-Jan-2015.) | 
| Ref | Expression | 
|---|---|
| notbid.1 | 
 | 
| Ref | Expression | 
|---|---|
| notbid | 
 | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | notbid.1 | 
. 2
 | |
| 2 | notbi 667 | 
. 2
 | |
| 3 | 1, 2 | syl 14 | 
1
 | 
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