Problem 6 : Following sentences are given in the Knowledge Base. 1- Vx.y (-Doctor(x) v ~Teacher(y)) v Earn More (x, y) 2- Vx Cardiologist(x)=>Doctor(x) 3- Vx Instructor(x) => Teacher(x) 4- Cardiologist(tom) Does Earn More (Tom, Ali)? Use Forward Chaining to prove your answer and state which inference rules you used in each step. (15 pts)