Bayesian Systems

• A Bayesian Net or belief net is a Directed Acyclic Graph.
• Nodes represent random variables.
• Arcs represent conditional dependencies.
• If you flip a coin, how likely is to be heads.
• If you flip two coins, how likely are they to both be heads. These are independent.
• If I roll a 6 sided die, how likely is it to be a 6?
• If I roll 2 dice, and one is a 6 how likely is the total to be 11? The result is dependent (not entirely) on the first roll.
• These are related to Hidden Markov Models.