Elamur Groupantsworld-store-coupling
The groupant beside world/src/store.rs in the Mova repository: what the code computes, what it never does, how to go back from its outputs, its invariants, cost and checks.
Facts
Implementation material. A Mova code model describes this code at one source revision: partial models, finite checks and their stated scope. It is not a reviewed general exposition, and its labels are shown as written, never raised.
Components
| component | label | where |
|---|---|---|
| approximant | partial | Forward |
| ast | partial | ../../syntax.json |
| cost | symbolic unmeasured | Cost |
| descriptant | present | model.md |
| invariant | partial | Invariant |
| tests | bounded evidence | ../../model.md#tests |
Obernants
The typed relations around the forward model: the behaviour complement (what the code never does), the reverse reconstruction (every input compatible with an output) and specialised views.
| id | type | label | where |
|---|---|---|---|
nonbehavior | behavior_complement | partial source derived model | nonbehavior |
antecedents | reverse_reconstruction | partial source derived model | antecedents |
positional-coupling | dependency_closure | partial source derived model | positional-coupling |
rank-boundary | counterfactual | partial source derived model | rank-boundary |
Model text
descriptant
coupling
Forward
Sampling advances a seed-derived xorshift stream once per ordered candidate, combines the state with ID salt, sorts key/ID pairs, takes k and sorts retained IDs. Filtering first changes stream positions and competitors.
Invariant
Sample output is sorted, unique and a subset of duplicate-free input candidates, of length min(k,n). Changed eligibility can change unchanged output membership. Reverse fibers retain candidate ordering and losing candidates.
Cost
O(n) pair allocation and O(n log n) sorting. This is the same sampling work modeled by the parent and must not be added again.
Epoch memory
2026-10-29: The removed-ID witness disproved that exact eligibility deltas suffice for sampled carry. Fixed-seed determinism does not imply candidate independence.
catalog
world-store-coupling
Source SHA-256 6801677c4f17273e615090a790f2e4018387ca5d006aab899bafda09f01b24d9. Conditional models over successful finite operations; I/O failure, malformed offsets and changing dependency state are excluded unless stated. Algebra is exact only for its declared abstract relation. Source correspondence remains bounded.
nonbehavior
Type: behavior_complement.
Universe: ordered duplicate-free candidate vectors, valid k and seed, and output vectors. Candidate inner complement includes sampled outputs longer than min(k,n), unsorted outputs, duplicate outputs, and IDs absent from candidates. This is a conditional source model of the sample stage, not the complement of the full query.
antecedents
Type: reverse_reconstruction.
Fix k and seed. A sampled observation Y has every ordered candidate vector C whose first min(k,|C|) pairs in sorted(key(C position,seed) xor id salt,id) have numerically sorted selected IDs equal to Y as compatible antecedents. Different candidate orders and losing candidates remain possible. No unique inverse; k=0 maps every candidate vector to empty.
positional-coupling
Type: dependency_closure.
The xorshift stream advances per candidate position. Removing one eligible ID changes ranks of later unchanged IDs as well as competition for k slots. Changed-ID dictionaries therefore do not bound output membership changes. Historical witness eligible [0,1,2] to [0,2], C={1}, pred>=1 sample=1/2 gives old [1], fresh [2], legacy merge []; repaired load must return [2].
rank-boundary
Type: counterfactual.
Hold query order and seed fixed, replace legacy delta-merge by complete target selection for stale sampled queries. Output equals F even if O\C differs from F\C. This intervention fixes candidate coupling but does not validate feature extraction, mutable same-hash indexes or forged stable stamps. Oracle compares repaired witness and rejects historical empty result.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/world/src/store.rs.groupant/selection.groupant/coupling.groupant/