Section 4 (40 Points): Use trees to assess the following arguments. If they are

Section 4 (40 Points):
Use trees to assess the following arguments. If they are not valid, provide a counterexample evaluation. Show all working
1. ~(p ∨ q), ~((r ∨ s) ∨ t), ~(~(q ∨ s) ∨ t) ∴ ~u
2. ((p ∨ q) –> (r&s)), (q ∨ t), ∼ t ∴ s

Use trees to check whether the following formula is satisfiable. If it is, describe an evaluation that makes it true. Show all working
1. ~(p ∨ ¬q) <--> ¬r
2. (p ∨ (q –> ∼ r)) & s