Let $X$ and $Y$ be two one-dimensional random variables in $R$ with joint distribution $P_{X,Y}$. The main assumptions usually involved in this problem setting include:

• Assumption 1: Identically and Distributed Samples
• Assumption 2: Time
• Assumption 3: Faithfulness
• Assumption 4: Selection Bias
• Assumption 5: Causal Sufficiency
• Assumption 6: Feedback Loops
• Assumption 7: Constraint Relation
• Assumption 8: Measurement Noise
• Assumption 9: Variable Units