The Rule of Inference finition(Modus Ponens From a and a-B, we can infer B. This rule is written as follows n→ BThe Rule of Inference . Definition (Modus Ponens) . . From α and α → β, we can infer β. This rule is written as follows: α α → β β Yi Li (Fudan University) Discrete Mathematics April 16, 2013 15 / 17