And Hidden Markov Models (HMMs) are just ones where the symbols are emitted upon interaction with an edge of the graph instead of the node. The nodes are still

And Hidden Markov Models (HMMs) are just ones where the symbols are emitted upon interaction with an edge of the graph instead of the node. The nodes are still the "states" of the system, but in general you can't know which state the model is in just by observing the symbols emitted by the edges as there may be equivalent structures in the graph associated with different states.