FA-65375 / Ecological population dynamics / Member archive

Ricker map trajectory and dynamic regime: exponent grouping · case 05

Populations above carrying capacity turn negative instead of being pulled down smoothly.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Regime by r: r<0 decline, r==0 neutral, 0<r<=1 monotone, 1<r<2 damped, 2<=r<2.526 cycle2, else complex; trajectory N[t+1]=N*exp(r*(1-N/K)) rounded 4; None for K<=0 or N0<0.

Why this case matters

Population projections set harvest quotas, conservation status and pest-control timing; a wrong update order, boundary or rate conversion silently changes management advice.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression: salmon stock damped	`["damped", [717.0703, 909.2473, 369.8138, 1044.4646, -208.1372, -1126.9578]]`	`["damped", [664.0234, 1099.1389, 947.2604, 1025.2415, 987.1493, 1006.3622]]`	Failed

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