begin name
fan1
end name

begin reactions
v1 {1.0}$EXTERNAL = {1.0}x
v2 {1.0}x = {1.0}y
v3 {1.0}x = {1.0}$EXTERNAL
v4 {1.0}y = {1.0}$EXTERNAL
end reactions

begin rate equations
v1 = lambda
v2 = beta*x[t]*y[t]
v3 = d*x[t]
v4 = a*y[t]
end rate equations

begin parameters
a = 0.4
beta = 0.2
d = 0.02
lambda = 0.2
default = 1.0
end parameters

begin initial conditions
x[0] = xi
y[0] = yi
end initial conditions

begin initial values
xi = 2.5
yi = 1.0
end initial values

begin assignment rules
end assignment rules

begin function definitions
end function definitions

begin events
end events

begin process annotations
end process annotations

begin species annotations
end species annotations

begin units
end units