Bayesian updating in causal probabilistic networks by local computations
(See the discussion on causality.) This can be used as a guide to construct the graph structure.
In addition, directed models can encode deterministic relationships, and are easier to learn (fit to data).
Moreover, the graphical model formalism provides a natural framework for the design of new systems." Probabilistic graphical models are graphs in which nodes represent random variables, and the (lack of) arcs represent conditional independence assumptions.
Hence they provide a compact representation of joint probability distributions.
For a directed model, we must specify the Conditional Probability Distribution (CPD) at each node.
If the variables are discrete, this can be represented as a table (CPT), which lists the probability that the child node takes on each of its different values for each combination of values of its parents.
In the rest of this tutorial, we will only discuss directed graphical models, i.e., Bayesian networks.
In addition to the graph structure, it is necessary to specify the parameters of the model.
The study of change impact is a fundamental activity in software engineering because it can be used to plan changes, set them up and to predict or detect their effects on the system and try to reduce them.
Various methods have been presented in the literature for this sector of maintenance.
The graphical model framework provides a way to view all of these systems as instances of a common underlying formalism.