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

# world-principles-list-boundary

The groupant beside world/src/principles.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/principles.rs`](https://github.com/ElamurAI/mova-free/blob/main/world/src/principles.rs)
- **source SHA-256:** `cdb5ef0db3da9ca5…`
- **covers:** For requested n and candidate count L, list_step=max(1,floor(L/n)) when n>0 and 1 when n=0. CLI list takes n items from indices 0,stride,2stride,... below L. Therefore n=0 emits none; positive limits preserve the previous spacing. Other CLI branches perform round or status I/O. (bytes 8476–9985)
- **part of:** [world-principles](https://md.groupants.elamur.ai/free/en/mova/world/src/principles.rs.groupant/)
- **repository folder:** [`world/src/principles.rs.groupant/list-boundary.groupant`](https://github.com/ElamurAI/mova-free/tree/main/world/src/principles.rs.groupant/list-boundary.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-principles-list-boundary-behavior-complement` | behavior_complement | partial source model | [behavior-complement](#behavior-complement) |
| `world-principles-list-boundary-reverse-reconstruction` | reverse_reconstruction | partial source model | [reverse-reconstruction](#reverse-reconstruction) |
| `world-principles-list-boundary-coupling` | constraint_relation | partial source model | [coupling](#coupling) |

## Model text


### forward

For requested n and candidate count L, list_step=max(1,floor(L/n)) when n>0 and 1 when n=0. CLI list takes n items from indices 0,stride,2stride,... below L. Therefore n=0 emits none; positive limits preserve the previous spacing. Other CLI branches perform round or status I/O.

### invariant

Stride is nonzero for all usize inputs. The selected iterator yields at most min(L,n) rows; output does not imply all pending facts were listed. A zero request still loads pending knowledge before selection; only the division panic is repaired.

### cost

Constant step calculation; O(min(L,n)) iterator observations after pending construction. No reduction of knowledge-loading cost is claimed.

### composition

Source callers: main dispatches main_args; family invokes round once per research round and reports returned counts/errors; round consumes pending and statement then external teacher/cache/world operations. Native public join: caller-supplied know::Fact -> statement. Selection tests call the exact private pure helper used by pending with supplied keys, avoiding filesystem state.

### epoch-memory

2026-10-30: initial source-bound review. Prospective cost model predicts no asymptotic change: selection helper extraction preserves sorting and cloning; list repair replaces one scalar division with checked division. Old zero-limit native witness divides by zero. Final implementation returns a nonzero stride and take(0) produces no rows. Mind production behavior is unchanged. No surrogate, speed or full-system correctness claim.

### checks

cargo test -p world --lib principles::wave12_models -- --test-threads=1. File evidence.md binds repeated native profiles and compiled production controls. Partial syntax leaves macros opaque; source-bound syntax is not semantic AST verification.

### behavior-complement

Domain and observation scope: Pure list_step(L,n) and step_by/take index observations for usize L,n; CLI loading excluded.

In U={(L,n,s,J)}, exclude s=0, s differing from max(1,floor(L/n)) for n>0, s differing from 1 for n=0, or J differing from the first n multiples of s below L. Any nonempty J for n=0 or L=0 is absent. 400 finite cases check this scalar/index relation; CLI load failures and load avoidance are not covered.

### reverse-reconstruction

For (s,J), retain every (L,n) satisfying the stride equation and exact bounded-multiple prefix; J alone existentially retains compatible s. Empty J admits n=0 and/or L=0. Nonempty J's last index is below L, while truncation permits multiple larger L,n pairs. Fact values are outside the index observation.

### coupling

400 finite L,n pairs compare actual step_by/take against independently constructed arithmetic indices, including twenty zero limits. Old arithmetic panics at L=n=0; checked_div repair preserves all positive n. CLI I/O remains unexecuted.

Typed entries bind the manifest source revision, this section's domain/operator/observation, and the named finite checks. Status is partial source-derived model. No complete reconstruction search, universal proof or factual-truth guarantee is claimed.