Evaluate each of the following arguments. If the argument is valid, use Fitch to give a formal proof using the rules you have learned. If it not valid, use Tarski's World to construct a counterexample world. In the lasttwo proofs you will need to use Ana Con to show that certain atomic sentences contradict one another to introduce 1. Use Ana Con only in this way. That is, your use of Ana Con should cite exactly two atomic sentences in support of an introduction of 1. If you have difficulty with any of these exercises, you may want to skip ahead and read Section 6.5. 6.9 Cube(b) 6.10 Cube(a) v Cube(b) - (Cube(c) A Cube(b)) -( Cube(c) A Cube(b)) - Cube(c) -Cube (c)