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

The groupant beside world/src/lessons.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:** [`world/src/lessons.rs`](https://github.com/ElamurAI/mova-free/blob/main/world/src/lessons.rs)
- **source SHA-256:** `c095c4c5f7556a32…`
- **covers:** Tokenize ASCII identifiers and integer strings, then precedence-climb with eager operands. Comparisons/Booleans return 0 or 1. Division requires zero remainder. Checked i64 add/subtract/multiply/negation/division/remainder propagate None on overflow. Entire token stream must be consumed. (bytes 5140–8252)
- **part of:** [world-lessons](https://md.groupants.elamur.ai/free/en/mova/world/src/lessons.rs.groupant/)
- **repository folder:** [`world/src/lessons.rs.groupant/eval.groupant`](https://github.com/ElamurAI/mova-free/tree/main/world/src/lessons.rs.groupant/eval.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 source model | [forward](#forward) |
| **ast** | partial | `../syntax.json` |
| **composition** | partial source model | [composition](#composition) |
| **cost** | partial source model | [cost](#cost) |
| **descriptant** | partial source model | [epoch-memory](#epoch-memory) |
| **invariant** | partial source model | [invariant](#invariant) |
| **tests** | partial source model | [checks](#checks) |

## 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 |
|---|---|---|---|
| `world-lessons-eval-behavior-complement` | behavior_complement | partial source model | [behavior-complement](#behavior-complement) |
| `world-lessons-eval-reverse-reconstruction` | reverse_reconstruction | partial source model | [reverse-reconstruction](#reverse-reconstruction) |
| `world-lessons-eval-coupling` | constraint_relation | partial source model | [coupling](#coupling) |

## Model text


### forward

Tokenize ASCII identifiers and integer strings, then precedence-climb with eager operands. Comparisons/Booleans return 0 or 1. Division requires zero remainder. Checked i64 add/subtract/multiply/negation/division/remainder propagate None on overflow. Entire token stream must be consumed.

### behavior-complement

U is finite expressions/environments with sufficient stack, paired with Option<i64>. Inner complement excludes Some for unknown symbols, invalid suffix, inexact or zero division and overflow. Eager evaluation excludes Some(0) for 0 && (1/0).

### reverse-reconstruction

B(v) is every syntactically accepted expression and environment evaluating to v. For v=2, 1+1 and 4/2 are compatible; unused bindings remain arbitrary. B(None) mixes syntax, missing-name, inexactness and overflow failures.

### coupling

Failure partition retains reasons only in the model: runtime None merges them. Literal positive 9223372036854775808 cannot be parsed, so MIN is accessible through an environment or representable computation, not that positive token followed by unary minus.

### invariant

Successful observations obey the declared forward relation with the same supplied state and order. Failure is explicit; no hidden label or retained-state guarantee is introduced.

### cost

Tokenization O(B); map probes O(log V); parser visits O(T) tokens, with recursive stack O(T) worst-case. Arbitrary nesting can exhaust the stack; no universal totality claim.

### composition

Evaluation and substitution share numeric bindings; field labels choose template containers. Child relations must agree on intermediate state, not merely final counts. Partial syntax binds the source; macro contents are opaque.

### epoch-memory

Initial review predicted arithmetic overflow and finite-pool boundary failures. Old native code failed six named witnesses: overflow, empty templates, name exhaustion, full-width range, reversed range and seed overflow. Narrow repairs retain public signatures; finite observations do not establish arbitrary-input totality. See file evidence.md for hashes and repeated results.

### checks

Eight wave12_models tests plus two existing lesson tests. Independent 19 by 19 by 7 arithmetic cases, precedence/eager failure literals, partition/substitution fixtures and exactly 2000 rejected RNG draws. Runtime guard mutations must fail named assertions. Evidence is finite; no whole-world or live course claim.