FA-64947 / Epidemic compartment models / Member archive

Reed-Frost expected chain-binomial generations: final size accounting · case 02

The final size misses the index cases.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Expected Reed-Frost: C[t+1] = S[t]*(1-(1-p)**C[t]), S[t+1]=S[t]-C[t+1]; cases are infectious for one generation only; stop early once expected cases fall below 1e-9; return [cases per generation including the index generation rounded to 4, final size including index cases rounded to 4]; None for invalid p or negative counts.

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: p zero no spread	`[[1.0, 0.0], 0.0]`	`[[1.0, 0.0], 1.0]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

Member access is invitation-based. Sign in with your invited account to inspect the sources.