Elamur Groupantsmova-elephant-part
The groupant beside tools/elephant/src/part.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 approximant |
| Ast | partial | syntax.json |
| Composition | partial | Composition |
| Cost | partial | Cost |
| Descriptant | present | Descriptant |
| Invariant | partial | Invariant |
| Tests | finite evidence | 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.
| relation | type | label | where |
|---|---|---|---|
| Behavior complement | behavior complement | partial source derived model | Behavior complement |
| Reverse reconstruction | reverse reconstruction | partial source derived model | Reverse reconstruction |
Model text
Descriptant
Reader and writer of word-graph parts and runs in both formats (WGPART01 without OOV frequencies, WGPART02 with them), independent of the wordgraph version's own reader. Source: tools/elephant/src/part.rs.
Forward approximant
open: magic -> format; next_oov: entries strictly sorted (checked), frequency u32::MAX in format 1; next_rec: strictly increasing keys (checked), the OOV table skipped if unread. Writer::start(format, n_oov, n) -> push_oov (strictly sorted) -> push(key, count>0, strictly increasing) -> finish: both counts met, fsync, rename from .tmp.
Invariant
A written run is sorted, unique, with positive counts and exactly the announced number of records; a reader never sees a half-written run (temporary file and rename); read_all(write(x)) = x.
Cost
Streaming: O(bytes) time, O(OOV table) memory.
Composition
Parent: elephant. Used by merge (runs), key (scans for list changes) and store (format and hashes).
Behavior complement
Never interprets a key beyond its packing; never writes in place. Evidence status: source-derived model with finite checks, not a proof.
Reverse reconstruction
A run decodes to its records exactly (round-trip test); the parts a run was merged from are not recoverable from it (the store's manifest keeps them).
Tests
Checks
part::tests: both formats round-trip; unsorted records, a short run and a zero count refused. These are finite fixtures and measurements; not a proof.
History
2026-11-06 · document
Epoch 2026-11-06
First model, written with the source (the Elephant made incremental and an animal on Mova).
Provenance
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/tools/elephant/src/part.rs.groupant/