Description: The zeroth bit of an even number is zero. (Contributed by Mario Carneiro, 5-Sep-2016) (Revised by AV, 19-Jun-2020)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | bits0eALTV | |- ( N e. Even -> -. 0 e. ( bits ` N ) ) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | evennodd | |- ( N e. Even -> -. N e. Odd ) | |
| 2 | evenz | |- ( N e. Even -> N e. ZZ ) | |
| 3 | bits0ALTV | |- ( N e. ZZ -> ( 0 e. ( bits ` N ) <-> N e. Odd ) ) | |
| 4 | 2 3 | syl | |- ( N e. Even -> ( 0 e. ( bits ` N ) <-> N e. Odd ) ) | 
| 5 | 1 4 | mtbird | |- ( N e. Even -> -. 0 e. ( bits ` N ) ) |