FA-5740 / Combinatorics / Member archive

Even subset count · case 05

Odd-cardinality subsets are included.

Member previewVariant 5 · 3 implementations · 4 checks per implementation

Case contract

Nonnegative integer counts. Permutation and combination counts are zero when a requested selection exceeds the available objects. Shape sizes satisfy the preconditions stated below. Even subset count. Exact operational definition: 1 if n==0 else 2**(n-1)

Why this case matters

Small exact fixtures expose this error without platform timing, external services, or probabilistic observations. Combinatorics results depend on the stated convention.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
fixture 2: (1,)	`2`	`1`	Failed

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