(86–90) : (i) All mountains are rivers → Universal Affirmative (A–type). (ii) Some hills are rivers → Particular Affirmative (I–type). (iii) No river is hill → Universal Negative (E–type). (iv) Some rivers are not hills → Particular Negative (O–type).
86. Some mountains are rivers. ↔ All rivers are hills. I + A ⇒ I–type of Conclusion “Some mountains are hills”. This is the Conclusion II. Conclusion I is the Converse of “All rivers are hills”.