Forgik is an educational application to learn and practice natural deduction.
By using inference rules, your goal is to prove a conclusion by assuming multiple premises.
Forgik uses a specific set of inference rules, including the law of excluded middle.
This set of rules is called classical logic and it allows proofs by contradiction.
Currently, Forgik only supports propositional logic.
But it will soon support first order logic, which is also called predicate logic.