Contact Process (mathematics)
The contact process is a model of an interacting particle system. It is a continuous time Markov process with state space, where is a finite or countable graph, usually Z. The process is usually interpreted as a model for the spread of an infection: if the state of the process at a given time is, then a site in is "infected" if and healthy if . Infected sites become healthy at a constant rate, while healthy sites become infected at a rate proportional to the number infected neighbors. One can generalize the state space to, such is called the multitype contact process. It represents a model when more than one type of infection is competing for space.
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