The model contains one compartment called C. There are four species called S1, S2, S3 and S4 and four parameters called k1, k2, k3 and k4. The model contains two reactions defined as:
Reaction | Rate |
S1 + S2 → S3 | k1 · S1 · S2 · C |
S3 → S1 + S2 | k2 · S3 · C |
The model contains one rule that determines the rate at which species S4 is changing:
Type | Variable | Formula |
Rate | S4 | k2 · add(S1, S2) |
The model contains two events that assign values to species S2 and S4:
Trigger | Delay | Assignments | |
Event1 | S1 < 0.75 | − | S2 = add(k3, k4) |
Event2 | S3 > 1.2 | − | S4 = 1 · divide(k3, k4) |
The rateRule and both eventAssignments use functionDefinitions defined as:
Id | Arguments | Formula |
add | x, y | x + y |
divide | x, y | xy |
The initial conditions are as follows:
Value | Units | |
Initial amount of S1 | 1.0 | mole |
Initial amount of S2 | 2.0 | mole |
Initial amount of S3 | 1.0 | mole |
Initial amount of S4 | 1.5 | mole |
Value of parameter k1 | 0.75 | litre mole-1 second-1 |
Value of parameter k2 | 0.25 | second-1 |
Value of parameter k3 | 0.5 | mole litre-1 |
Value of parameter k4 | 0.5 | mole litre-1 |
Volume of compartment C | 1 | litre |
The species values are given as amounts of substance to make it easier to use the model in a discrete stochastic simulator, but (as per usual SBML principles) their symbols represent their values in concentration units where they appear in expressions.