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.下标（subscript）代表细胞索引；上标（superscript）代表时间。需注意，所有节点均已分配数值索引（numerical index），本文后续将统一使用该索引以方便指代。细胞外节点（extracellular nodes）及相邻细胞的索引规则如下：按顺序，16至21分别对应、、、、和。