FA-72095 / Error-correcting codes / Member archive

Min-sum sign includes the edge own message · case 05

Outgoing messages point back towards the incoming belief instead of the extrinsic one.

Member previewVariant 5 · 3 implementations · 8 checks per implementation

Case contract

Offset min-sum check-node update for LDPC decoding with integer LLRs. For each edge i the outgoing message is the product of the signs of all OTHER incoming LLRs (0 counts as positive) times max(min |other LLR| - beta, 0). Fewer than two edges returns None. Return the outgoing messages in edge order.

Why this case matters

LDPC decoders in Wi-Fi, 5G and SSD controllers run this update billions of times per second.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
regression [[-1, 2, -7], 1]	`[1, 0, 0]`	`[-1, 0, 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.