---
title: "langseg-latin-eval — Mova code model"
description: "Mova code model of tools/langseg/src/latineval.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/tools/langseg/src/latineval.rs.groupant/"
---
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# langseg-latin-eval

The groupant beside tools/langseg/src/latineval.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

- **kind:** groupant
- **status:** partial source bound model
- **source:** [`tools/langseg/src/latineval.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/langseg/src/latineval.rs)
- **repository folder:** [`tools/langseg/src/latineval.rs.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/langseg/src/latineval.rs.groupant)

> **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 | [Approximant](#approximant) |
| **Ast** | partial | `syntax.json` |
| **Cost** | symbolic source derived | [Cost](#cost) |
| **Descriptant** | present | [Descriptant](#descriptant) |
| **Invariant** | partial | [Invariant](#invariant) |
| **Tests** | executed bounded checks | [Tests](#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](#behavior-complement) |
| Reverse reconstruction | reverse reconstruction | partial source derived model | [Reverse reconstruction](#reverse-reconstruction) |
| Held out protocol | held out protocol | partial source derived model | [Held out protocol](#held-out-protocol) |

## Model text


### Descriptant

The measurement commands of the Latin table: `latin-eval` (UD EWT + GSD sentences of a split, optional dev halves,
synthetic code-switched mixtures, sweeps, the shuffled-lexicon negative control), `latin-pairs` (a parallel corpus as
labelled out-of-domain data, with dialect counts) and `latin-lexicon` (a lexicon file from CoNLL-U).

### Approximant

Sentence and token confusion matrices; switch points `P = TP/predicted`, `R = TP/gold`, `F1`; fragments whole =
share of mixtures whose inserted tokens are all labelled right. Mixtures: a seeded `Rng` picks a donor sentence of the
other language, 2–8 consecutive words, an insertion gap and a wrapper (bare, « », "").

### Invariant

The test split is refused; dev halves are disjoint by `fnv(text) mod 2`; the same split and seed give byte-identical
reports (checked twice 2026-11-06); the negative control keeps each language's number of types.

### Cost

`O(S · n · K)` after the table build; the sweep multiplies by the grid size (9 × 5).

### Behavior complement

It does not read test splits; it does not tune anything itself (sweeps print, a person picks); it does not measure
real code-switched text (mixtures are synthetic) or dialect accuracy on labelled dialect data (none on disk).

### Reverse reconstruction

A report recovers the confusion counts and rates, not which sentences erred (unless `--errors N` prints them).

### Held out protocol

Parameters were chosen on dev half a; half b and the whole dev are reported. Train sentences cannot serve for the
choice: their words, names included, are in the lexicons (train sweep 2026-11-06: 99.6% for every cap value).

### Tests

Run outputs in the README of langseg (2026-11-06); determinism by two identical runs; red control `--shuffle`
(55.02% of sentences against a majority class of 57.28%).

## Provenance

- **source SHA-256:** `f944039675ad6fa1…`
- **repository commit:** `2e25d7bfae9a`