What does this equation mean?

where n is the growth rate of the population of researchers, $\phi$ measures how much easier or harder each new idea makes the next one to find (values below 1 are required for the model’s growth path to be stable at all — the discipline’s own name for this is diminishing returns to knowledge accumulation), and $\lambda$ measures how much duplicated research effort — different teams stumbling onto the same idea — dilutes each additional researcher’s marginal contribution. The formula says something that should be intuitive from the fitness-landscape framing: if the population of people searching for new technology stops growing, n falls toward zero, and the long-run growth rate of ideas falls with it, one for one, unless something else changes $\lambda$ or $\phi$ .