FA-74890 / CRDT convergence / Member archive

PN-Counter with local floor: negative slots flow against the sync direction · case 05

Receivers do not see the sender's decrements while the sender absorbs the receiver's.

Member previewVariant 5 · 3 implementations · 9 checks per implementation

Case contract

Replicas keep a positive map and a negative map (replica->total). ["inc", r, k] and ["dec", r, k] need k > 0, otherwise the event index is rejected. A decrement is also rejected when r's locally observed value is below k. ["sync", src, dst] merges both maps of src into dst by pointwise maximum. Return values and rejected indices.

Why this case matters

Positive/negative counters are the standard way to support decrements in a state-based counter.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
decrement funded by learned increments	`{"rejected": [], "values": [7, 1, 7]}`	`{"rejected": [], "values": [1, 1, 1]}`	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.