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This wrap-up explores essential distinctions in probabilistic graphical models, covering template-based versus specific models, directed versus undirected graphs, as well as generative and discriminative approaches. We also delve into variable types, including target, observed, and latent variables, while discussing causal versus non-causal ordering. Important concepts such as parameters, local structure, structured conditional probability distributions (CPDs), and the processes of model testing and iterative refinement are highlighted. This comprehensive overview serves as a foundation for advancements in knowledge engineering.
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Representation Probabilistic Graphical Models Wrapup Knowledge Engineering
Important Distinctions • Template based versus specific • Directed versus undirected • Generative versus discriminative • Hybrids are also common
Important Distinctions Template-based Specific
Important Distinctions Generative Discriminative
Variable Types • Target • Observed • Including complex, constructed features • Latent GMT … W1 W2 W3 Wk
Structure • Causal versus non-causal ordering GMT … … W1 W1 W2 W2 W3 W3 Wk Wk GMT
Parameters: Values • What matters: • Zeros • Orders of magnitude • Relative values • Structured CPDs
Parameters: Local Structure • Table CPDs are the exception
Iterative Refinement • Model testing • Sensitivity analysis for parameters • Error analysis • Add features • Add dependencies