FA-13077 / Numerical aggregation / Member archive

Merge cross scatter: The x centroid moves according to old rather than incoming population. · case 02

The reduction disagrees with its explicit aggregation oracle.

Member previewVariant 2 · 3 implementations · 6 checks per implementation

Case contract

Merge disjoint integer (x,y) observation blocks. Return count, exact x/y means and unnormalised centered cross scatter as Fraction strings; empty summary is zero.

Why this case matters

Exact bounded examples isolate a reduction defect without floating-point or external-service effects.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression 1	`[4, "27/4", "13/4", "-141/4"]`	`[4, "19/4", "13/4", "-111/4"]`	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.