Boolean logic formulae representing the state-transition functions for each node in the SPN (four-cell parasegment) model.

The subscript represents the cell index; the superscript represents time. Note that every node has a numerical index assigned to it, which we use for easy referral throughout the present work. The extra-cellular nodes, and in adjacent cells are indexed as follows: 16 to 21 denote , , , , and in this order.