# Jitpro Exercises 3: Refuing PLNc Formulas

In each example, you will refute a set *A* of closed PLN formulas.
The elements of *A* are given as axioms. To put each formula on the branch,
press the button that says **Import Axiom or Lemma**
and choose the formula to import. (You can ignore "claim false" which will put ¬false on the branch.)

## Jitpro Exercise 3.1

## Jitpro Exercise 3.2

## Jitpro Exercise 3.3

## Jitpro Exercise 3.4