Affirmative conclusion from a negative premise

The fallacy, Affirmative conclusion from a negative premise is when a positive claims is made from one or more negative premises.

For instance, the formal structure might be:
 * A != B and B != C, therefore C = A

Examples

 * Atheists are not good. Christians are not atheists. Thus, Christians are good.
 * Evolution is not true. Intelligent design is not evolution. Therefore, Intelligent design is true.