Homework for Philosophy 270, Fall 2011

Use a derivation to show the following argument is not formally valid and present a counterexample that divides a dead-end gap:

¬ ((A ∧ B) ∧ ¬ C), A ⊨ C

Again, list, for each stage and for the gap you work on at that stage, the proximate argument (i.e., the argument formed from the active resources and the goal) that the gap had before you applied a rule at that stage.