The model contains three varying parameters called S1, S2 and S3 and two constant parameters called k1 and k2. (Note that indeed S1, S2 and S3 are parameters and not species in this model.)

The model contains three rules defined as:

Type Variable Formula
Rate S1 k2 · S3 − k1 · S1 · S2
Rate S2 k2 · S3 − k1 · S1 · S2
Rate S3 k1 · S1 · S2 − k2 · S3

The model contains two events that assign values to parameters S2 and S1:

Trigger Delay Assignments
Event1 S1 < 0.75 1 S2 = 1
Event2 S3 > 1.4 1.5 S1 = 1

The initial conditions are as follows:

Value Units
Initial amount of S1 1.0 any
Initial amount of S2 2.0 same as S1
Initial amount of S3 1.0 same as S1
Value of parameter k1 0.75 (unit of S1)-1 second-1
Value of parameter k2 0.25 second-1