---
title: "latex-ast-stage0 — Mova code model"
description: "Mova code model of latex/src/ast.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/latex/src/ast.rs.groupant/stage0.groupant/"
---
Elamur: [Mova](https://md.mova.elamur.ai/free/en/) · [Dictionary](https://md.dictionary.elamur.ai/free/en/) · [Research](https://md.research.elamur.ai/free/en/) · **Groupants**

This page as HTML: <https://groupants.elamur.ai/free/en/mova/latex/src/ast.rs.groupant/stage0.groupant/>

# latex-ast-stage0

The groupant beside latex/src/ast.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_fragment
- **status:** partial source bound model
- **source:** [`latex/src/ast.rs`](https://github.com/ElamurAI/mova-free/blob/main/latex/src/ast.rs)
- **source SHA-256:** `88786b90964d7ee3…`
- **covers:** empty()=Row([]). norm(v)=v[0] when len(v)=1, otherwise Row(v); singleton extraction consumes the vector by pop. (bytes 3520–3766)
- **part of:** [latex-ast](https://md.groupants.elamur.ai/free/en/mova/latex/src/ast.rs.groupant/)
- **repository folder:** [`latex/src/ast.rs.groupant/stage0.groupant`](https://github.com/ElamurAI/mova-free/tree/main/latex/src/ast.rs.groupant/stage0.groupant)
- **repository commit:** `855da7bd4a7b`

> **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` |
| **composition** | partial | [composition](#composition) |
| **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.

| id | 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) |
| `singleton_quotient` | singleton_quotient | partial source derived model | [singleton_quotient](#singleton-quotient) |
| `empty_identity` | empty_identity | partial source derived model | [empty_identity](#empty-identity) |

## Model text


### descriptant

#### latex-ast-stage0

empty()=Row([]). norm(v)=v[0] when len(v)=1, otherwise Row(v); singleton extraction consumes the vector by pop.

Epoch 2026-10-31: replaced stage topic lists with concrete transitions, exclusions and compatible antecedents. Four meaningful typed views replace the previous six-view bookkeeping catalog. Shared syntax and source byte bounds are unchanged.

### approximant

#### Scoped forward relation

empty()=Row([]). norm(v)=v[0] when len(v)=1, otherwise Row(v); singleton extraction consumes the vector by pop.

This is an exact source-derived partial model, not an executable approximate replacement.

### invariant

#### Scoped invariants

norm([Char(x)]) cannot yield Row([Char(x)]); norm([]) cannot invent an atom. Existing nested Row nodes are not recursively flattened.

norm([Row([a,b])]) and norm([a,b]) both produce Row([a,b]); this is an outer-list quotient, not recursive semantic simplification.

empty and norm([]) are structurally identical, but norm([Group(empty())]) preserves Group(empty()) rather than equating explicit braces to an empty row.

### composition

#### Scoped interaction

Parser list/table routines use norm after collecting atoms. These constructors do not enforce invariants on manually constructed Node::Row values.

The manifest binds this stage to the unchanged parent syntax projection and exact source byte range. Parent cost remains an upper accounting context; no independent whole-file invocation or execution count is assigned to this fragment.

### models

### behavior_complement

norm([Char(x)]) cannot yield Row([Char(x)]); norm([]) cannot invent an atom. Existing nested Row nodes are not recursively flattened.

### reverse_reconstruction

For non-Row atom a, norm inverse is exactly {[a]}. For Row(v), compatible lists include v when len(v)!=1 and [Row(v)] always. Thus Row([]) can come from [] or [Row([])]; normalization loses that outer-list provenance.

### singleton_quotient

norm([Row([a,b])]) and norm([a,b]) both produce Row([a,b]); this is an outer-list quotient, not recursive semantic simplification.

### empty_identity

empty and norm([]) are structurally identical, but norm([Group(empty())]) preserves Group(empty()) rather than equating explicit braces to an empty row.

### tests

#### Evidence — 2026-10-31

ast::wave28_tests::normalization_and_span_quotient; ast::wave28_tests::traversal_preserves_script_and_unknown_order

Selected library filters ast:: lex:: macros:: parse:: print:: table:: and integration gate excluding document_extraction_with_preamble_macros and random_token_soup_never_panics_and_roundtrips. Direct rustc --test latex/build.rs exercises private helpers. All selected tests twice debug/release with identical sorted names. Four compiled mutants at build/AST/parser/printer boundaries fail assertions then exact restoration passes. These do not individually cover every source. Build-main failure effects, allocation failures and universal roundtrip are unproved. Strict Clippy reports existing lints. No corpus/live VMM/API/GPU/full-school/held-out tests.