FA-12447 / Molecular graph representation / Member archive

Neighbor count replaces encoded bond order · case 02

Neighbor count replaces encoded bond order.

Member previewVariant 2 · 3 implementations · 6 checks per implementation

Case contract

For an atom ID, sum integer orders 1..3 of incident undirected bonds [a,b,order]; unique endpoints and no self bonds. This is an order sum, not inferred valence.

Why this case matters

Controlled molecular graph interchange model; tests isolate atom or bond representation errors without claiming chemical validity or production toolkit equivalence.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
double	`1`	`2`	Failed

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

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