---
title: "translation-meta-fwt-function_apply — Mova code model"
description: "Mova code model of tools/translate/src/fwt.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/tools/translate/src/fwt.rs.groupant/function_apply.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**

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# translation-meta-fwt-function_apply

The groupant beside tools/translate/src/fwt.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:** [`tools/translate/src/fwt.rs`](https://github.com/ElamurAI/mova-free/blob/main/tools/translate/src/fwt.rs)
- **source SHA-256:** `9e51710f505e2d8f…`
- **covers:** Clone/substitute, mark function drops, emit insertion runs before source i then kept i, build new_of, climb dropped heads and attach inserted tokens to nearest directional kept neighbor. (bytes 6127–8288)
- **part of:** [translation-meta-fwt](https://md.groupants.elamur.ai/free/en/mova/tools/translate/src/fwt.rs.groupant/)
- **repository folder:** [`tools/translate/src/fwt.rs.groupant/function_apply.groupant`](https://github.com/ElamurAI/mova-free/tree/main/tools/translate/src/fwt.rs.groupant/function_apply.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` |
| **cost** | symbolic source derived | [invariant](#invariant) |
| **descriptant** | present | [descriptant](#descriptant) |
| **invariant** | partial | [invariant](#invariant) |
| **tests** | bounded native receipts | [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) |
| `substitution_context` | substitution_context | partial source derived model | [substitution_context](#substitution-context) |
| `synthetic_span` | synthetic_span | partial source derived model | [synthetic_span](#synthetic-span) |
| `head_climb` | head_climb | partial source derived model | [head_climb](#head-climb) |
| `boundary_insert` | boundary_insert | partial source derived model | [boundary_insert](#boundary-insert) |

## Model text


### descriptant

#### Description and epoch memory

Clone/substitute, mark function drops, emit insertion runs before source i then kept i, build new_of, climb dropped heads and attach inserted tokens to nearest directional kept neighbor.

##### Prospective epoch 2026-10-31

Models predicted metadata loss, bounded coordinate transport and deterministic tie selection before test changes. Production bytes are preserved; only five inline synthetic tests were appended across the group.

##### Observation epoch 2026-10-31

Selected named native tests are bound in tests.md; raw receipts are external under $MOVA_DATA/runs/octopus-wave32-tr_meta-2026-10-31. Syntax is generated twice and byte-compared. This is partial syntax without macro expansion or semantic resolution.

##### Gaps

No real annotator/model loads, corpus translation, teacher calls, GPU, full training/evaluation, or language-accuracy claim. No executable percentage surrogate is supplied: an appropriate reference metric/domain is not established. Supported future caps are1/2/5/10 percent only. Residual reconstruction is conditional on retained diagnostics and is not persistent learning.

### approximant

#### Forward relation

Clone/substitute, mark function drops, emit insertion runs before source i then kept i, build new_of, climb dropped heads and attach inserted tokens to nearest directional kept neighbor.

### invariant

#### Invariant and cost

##### Domain and preservation

In-range heads, finite strings; malformed insertion tag defaults IN; cycles through dropped nodes stop after n+1 checks.

##### Cost

O(n²+I*n) worst-case, plus lookup/key/output byte work; O(n+I) coordinates.

Counters and allocation arithmetic must remain representable. String/map costs include compared bytes; finite evidence is not a throughput estimate.

### models

## Typed models

Subject: exact source hash in manifest; observation is one call or the stated finite training pass. All models are partial source-derived relations, not universal proof. Domain and resource assumptions are in invariant.md. The baseline exclusion is an inner source-derived claim on that domain; reverse is a compatible-antecedent relation. Specialized relations hold fixed the parameters and tables unless stated otherwise. Evidence uses the named checks in tests.md; individual assertions cover only finite parts, other branches remain prospective.

### behavior_complement

A content token cannot be dropped by drops set alone. Deleted positions are never returned as output head indices.

### reverse_reconstruction

For fixed table, compatible originals include dropped chains leading to each output head and substitutions mapping into emitted concepts; spans of inserts are always(0,0).

### substitution_context

Keys observe substituted neighbors, not originals.

### synthetic_span

Inserted MTok carries span(0,0), relation Det even default IN tag.

### head_climb

Kept token heads follow removed ancestors until kept/root; bounded cycles root.

### boundary_insert

Loop includes i=n, enabling suffix inserts and empty-sequence key ^|$.

### tests

#### Checks and evidence

- fwt::tests::a_fronted_part_moves_after_its_root
- fwt::tests::drops_and_inserts

Exact cargo commands use package translate, binary translate, --offline --locked and -- --exact --test-threads=1. External native-commands.json lists every name; debug and release run twice, numerical status and named outcomes retained. Some tests target other portions of the file; this fragment has source reasoning plus only the overlapping assertions.

Compiled controls mutate production decision expressions and restore exact original bytes; see external mutations.json and restoration receipt. No assertion-only mutation is counted. The evidence summary is authoritative for completed receipts. Scoped source reasoning and finite tests do not establish total branch coverage.