All cell phones are wireless devices. Therefore, some cell phones are wireless devices ∴ not deductive; counter-example with empty set of cell phones
Argument: The Democrats will win the election. Therefore, they will win the election whether they win a majority or not. (D, M) Answer: D ∴(M →D) ∧(¬M →D)
Argument: America will win the Olympics unless China does. China will win the Olympics unless Germany does. So America will win the Olympics unless Germany does. (A, R, E) Answer:
¬R →A ¬E →R ∴¬E →A
or
(P→¬Q)∧(Q→¬P)
{C} and {A, B} would both be preferred extensions simultaneously.