How do you encode a probability transition matrix, which is a probability of going from State A to State B?
The issue here is that I can only use the State index once. I need it twice.
An array may only use an Index once to identify a dimension. In Analytica, you identify indexes of a multidimensional array by the name of the index, rather than position (which is common in other languages). But there's a simple way to address your problem -- where you want to create a 2D matrix indexed by original State and Next State. Given that you have an Index State, you define a second index,
   INDEX NextState := CopyIndex(State)
You can then define the matrix as, say of transition probabilities as:
   Variable TransitionProb := Table(State, NextState)(....)
See more details on the Analytica wiki at CopyIndex
Cheers
Max
