Defining Faithfulness ::: Assumption 1 (The Model Assumption).
Two models will make the same predictions if and only if they use the same reasoning process. Defining Faithfulness ::: Assumption 2 (The Prediction Assumption).
On similar inputs, the model makes similar decisions if and only if its reasoning is similar. Defining Faithfulness ::: Assumption 3 (The Linearity Assumption).
Certain parts of the input are more important to the model reasoning than others. Moreover, the contributions of different parts of the input are independent from each other. 
 Question: Which are three assumptions in current approaches for defining faithfulness?
Two models will make the same predictions if and only if they use the same reasoning process. On similar inputs, the model makes similar decisions if and only if its reasoning is similar. Certain parts of the input are more important to the model reasoning than others. Moreover, the contributions of different parts of the input are independent from each other.