,13.3 INFERENCE USING FULL JOINT
DISTRIBUTIONS
• Inference-Figuring something out from facts or evidence.
• Example: If the ground is wet, you infer it rained.
• Probabilistic Inference:Instead of being 100% sure, you cal
how likely something is based on available information.
• Example: “There’s a 60% chance you have a cavity if your t
hurts.”
• It uses a full joint probability distribution as a knowledge b
• Answers are derived by summing or conditioning over rele
probabilities.
,Posterior Probability:
• This is the “updated probability” of something after considering
evidence.
• Example: Before going to the dentist, you think the chance of a cav
is 20%. After feeling pain, that rises to 60%.
• “There’s a 60% chance you have a cavity if your tooth hurts.”s
, Joint Probability Distribution:
• A giant table showing all possible combinations of events and their
probabilities.
• Example: Toothache + Cavity + Probe-Catch
• Probability = 0.108.