Function cycle_period 

pub fn cycle_period(
    g: &MarkedGraph,
    delay: impl Fn(&Transition) -> f64,
) -> Period

The spatial clock. The maximum cycle mean of g under delay, by parametric search: for a candidate period λ, give each edge the weight delay(producer) − λ·tokens. A positive-weight cycle exists exactly when some cycle’s mean exceeds λ, so Bellman-Ford’s longest-path relaxation decides the comparison and bisection converges on Π.

Deterministic: the same graph and the same delays give the same period, bit for bit.