Question Number 201308 by Mingma last updated on 04/Dec/23
Commented by aleks041103 last updated on 04/Dec/23
$$−{Q}\Leftrightarrow−{Q} \\ $$$${Q}\Leftrightarrow−\left(−{Q}\right) \\ $$$${P}\Rightarrow{Q}\Leftrightarrow−\left(−{Q}\right) \\ $$$$\therefore{P}\Rightarrow−\left({Q}\right) \\ $$
Commented by Mingma last updated on 04/Dec/23
use the natural deduction rules
Answered by aleks041103 last updated on 04/Dec/23
$${This}\:{sign}\:\supset\:{is}\:{from}\:{set}\:{theory}. \\ $$$${What}\:{is}\:{the}\:{connection}\:{to}\:{logic}? \\ $$
Commented by Mingma last updated on 04/Dec/23
implication sign