---
title: "math-understand-frames — Mova code model"
description: "Mova code model of math/src/understand.rs: components with their labels, obernants and the model text."
url: "https://groupants.elamur.ai/free/en/mova/math/src/understand.rs.groupant/frames.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/math/src/understand.rs.groupant/frames.groupant/>

# math-understand-frames

The groupant beside math/src/understand.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:** [`math/src/understand.rs`](https://github.com/ElamurAI/mova-free/blob/main/math/src/understand.rs)
- **source SHA-256:** `5b3ac990c5e46e75…`
- **covers:** Interp first rejects unknown words/symbols, then requires a quantity. It selects chance, percent change/share, percent adjustment, comparison, temperature-state, then source/conversion in order. default_scale is the first explicit quantity Scale, never a bare target. (bytes 19246–41081)
- **part of:** [math-understand](https://md.groupants.elamur.ai/free/en/mova/math/src/understand.rs.groupant/)
- **repository folder:** [`math/src/understand.rs.groupant/frames.groupant`](https://github.com/ElamurAI/mova-free/tree/main/math/src/understand.rs.groupant/frames.groupant)
- **repository commit:** `48f2e6f74146`

> **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` |
| **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) |
| `condition_selection` | condition_selection | partial source derived model | [condition_selection](#condition-selection) |
| `scale_transport` | scale_transport | partial source derived model | [scale_transport](#scale-transport) |

## Model text


### descriptant

#### math-understand-frames

Interp first rejects unknown words/symbols, then requires a quantity. It selects chance, percent change/share, percent adjustment, comparison, temperature-state, then source/conversion in order. default_scale is the first explicit quantity Scale, never a bare target.

Epoch 2026-10-31: replaced duplicate catalog sentences with concrete exclusions, compatible-antecedent examples and two distinct scoped behavioral views. Source and prior execution evidence are unchanged; this revision ran no tests.

### approximant

#### Scoped forward relation

Interp first rejects unknown words/symbols, then requires a quantity. It selects chance, percent change/share, percent adjustment, comparison, temperature-state, then source/conversion in order. default_scale is the first explicit quantity Scale, never a bare target.

This source-derived relation is partial; no executable percentage surrogate or replacement is supplied.

### invariant

#### Scoped domain and invariants

Nonempty Sent list and valid head indices are required. Error reasons encode first selected failure, not all possible failures. Downstream eval remains responsible for arithmetic/dimensional validity.

##### Cost

Repeated item cloning/scanning and subtree membership contribute costs; function subtree fallback and Rat duration conversion are distinct operations. Annotation cost is outside this fragment.

### models

### behavior_complement

Unknown alphabetic token cannot reach frame dispatch. A bare Fahrenheit target cannot supply a source scale for20 degrees. Later frame triggers cannot override an earlier selected frame, even if the earlier frame fails.

### reverse_reconstruction

The same Expr may originate from a direct quantity, a sole condition quantity, or different synonym-based function frames. An unknown-word error admits sentences with or without numbers because that gate runs first.

### condition_selection

All preceding sentence items are conditions; in the last sentence only cond=true items qualify. A lone condition quantity can supply source; multiple earlier-sentence quantities can fail as ambiguous.

### scale_transport

A Scale quantity becomes Temp unless delta=true, when it becomes Qty with the delta unit. Degrees uses default_scale or fails; it does not infer source scale from conversion destination.

### tests

#### Scoped evidence

Unknown/empty/ambiguous source scale and source-to-chain path; most frame branches and annotation unexecuted.

Named actual source fixtures: understand::wave28::{rejection_precedence_and_scale_ambiguity; pratt_precedence_and_percent_rewrite}.

Parent tests.md records commands and paired profiles. No additional coverage inferred from parent fixtures outside this byte range; source-scoped numeric/parse properties remain partial.