Chapter 2 - The Logic of Compound Statements - Exercise Set 2.3 - Page 62: 22

invalid argument

Let p represent “Tom is on team A” and q represent “Hua is on team B.” Then the argument has the form ∼p →q ∼q → p ∴∼p ∨ ∼q The first row shows that it is possible for an argument of this form to have true premises and a false conclusion. Thus this argument form is invalid.