FA-65310 / Epidemic compartment models / Member archive

Two-patch SIR with daily migration: simultaneous exchange · case 05

Migration creates or destroys people when flows are applied sequentially.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Each day: local frequency-dependent SIR in each patch using the current patch size, then every compartment exchanges fraction travel of each patch simultaneously; return [S pair, I pair, R pair] rounded 3.

Why this case matters

Compartmental epidemic calculations drive outbreak forecasts, vaccine targets and hospital planning; a single wrong flow, rate conversion or boundary silently changes every downstream number.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression: city and town	`[[609.949, 389.059], [74.517, 36.215], [52.35, 24.752]]`	`[[611.99, 397.105], [74.874, 37.65], [52.607, 25.773]]`	Failed

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