FA-65097 / Epidemic compartment models / Member archive

Age-structured force of infection: prevalence denominator · case 02

Small age bands receive inflated force of infection from large ones.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

lambda[a] = beta*susceptibility[a]*sum_b contacts[a][b]*infected[b]/sizes[b] (groups with zero size skipped); expected new infections susceptible[a]*(1-exp(-lambda[a])); return [lambdas rounded 6, new infections rounded 4, total rounded 4].

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: three age bands	`[[0.02825, 0.01448, 0.0114], [5.0138, 6.4691, 3.2872], 14.7701]`	`[[0.019, 0.0166, 0.0087], [3.3877, 7.4083, 2.5121], 13.3081]`	Failed

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