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How many probabilities do we need to explicitly specify for a whole Bayesian network?

a) Equal to the number of nodes in the network
b) Equal to the number of edges in the network
c) Equal to the square of the number of nodes in the network
d) Equal to the number of states for each node in the network

User Tomer Mor
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1 Answer

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Final answer:

To determine the number of probabilities needed for a complete Bayesian network, one must consider the conditional probability distributions for each node, given its parents. None of the provided options a), b), c), or d) directly answer the question, as the number required is the sum of the products of the states of each node and its parent nodes' states. This is generally taught at the college level in advanced statistics or computer science courses.

Step-by-step explanation:

The student is asking about the number of probabilities that need to be specified for a complete Bayesian network. This question falls under the subject of Mathematics, particularly in the area of probability and statistics. The grade level for this type of question is typically College because Bayesian networks are usually covered at an advanced level of statistical learning.

To specify a Bayesian network completely, one must define the probability distribution for each node, conditional on its parent nodes. This means you need to know the conditional probability of each node given each possible combination of values of its parent nodes. If a node has no parents (i.e., it's a root node), you need to specify its marginal probability distribution.

The correct answer is not dependent on the number of nodes, edges, or square of the nodes. Instead, the number of probabilities needed is equal to the sum of the product of the number of states for each node and the number of states for all its parent nodes across the network. Therefore, none of the options a), b), c), or d) explicitly gives the right method for calculating the total number of probabilities needed for a complete specification of a Bayesian network. However, you can consider that the number of probabilities is related to the number of states for each node and their respective parents, which can be considerably less than the square of the number of nodes, but typically more than just the number of nodes or edges.

User Sjoerd Perfors
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