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

# prag-infer-ancestry

The groupant beside prag/src/infer.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:** [`prag/src/infer.rs`](https://github.com/ElamurAI/mova-free/blob/main/prag/src/infer.rs)
- **source SHA-256:** `723690dfeebf9e8b…`
- **covers:** Bounded ancestor climb used by factive clause token filtering. (bytes 7251–7756)
- **part of:** [prag-infer-presupposition](https://md.groupants.elamur.ai/free/en/mova/prag/src/infer.rs.groupant/presupposition.groupant/)
- **repository folder:** [`prag/src/infer.rs.groupant/presupposition.groupant/ancestry.groupant`](https://github.com/ElamurAI/mova-free/tree/main/prag/src/infer.rs.groupant/presupposition.groupant/ancestry.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** | bounded executed evidence | `../../model.md#evidence` |

## 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 |
|---|---|---|---|
| `prag-infer-ancestry-behavior-complement` | behavior_complement | partial source model | [behavior-complement](#behavior-complement) |
| `prag-infer-ancestry-reverse-reconstruction` | reverse_reconstruction | partial source model | [reverse-reconstruction](#reverse-reconstruction) |
| `prag-infer-ancestry-broken-parent` | failure_partition | partial source model | [broken-parent](#broken-parent) |

## Model text


### forward

For fixed words W of length n and selected in-range top j, under(k) starts x=k. For at most n iterations: return true when x=j; otherwise follow a parent h only if 1<=h<=n, setting x=h-1; return false on missing/root/out-of-range parent. Exhaustion returns false. For functional in-range parent graphs, any first reach of top occurs within n distinct vertices.

### behavior-complement

Universe: (W,k,j,b), with k,j supplied valid token coordinates and b Boolean. An inner bound of absent triples includes b=true when the path terminates at root or a dangling parent before top, and b=true for a cycle disjoint from top. Bounds are source-derived; malformed parent values are tolerated as absent evidence. The literal seven-token clause fixture includes a dangling branch and a two-node cycle and excludes both from content.

### reverse-reconstruction

Given true, compatible graphs include k=j as well as every graph with a parent chain from k reaching j under the bound. Given false, compatible graphs include roots, dangling edges and disjoint cycles. The Boolean erases hop count and all off-path parents. Neither answer recovers a unique dependency tree. A graph with top itself in a cycle may still give true: the relation is reachability to top, not global well-formedness.

### broken-parent

Hold a path prefix from k fixed. Outcomes partition into reaches-top, stops-at-root, stops-at-out-of-range, or exhausts-hop-bound. Root and broken-parent termination map to the same false observation, but have different repair hypotheses. A dangling unrelated branch should not abort the whole presupposition call; the old fixture did panic and the repaired fixture renders exactly she ran.

### invariant

Every indexed current coordinate is checked through get; only a bounded nonzero parent is followed. At most n steps, so non-reaching cycles terminate. Parent coordinates are one-based; selected top and current x are zero-based.

### composition

This predicate is private inside presuppositions and executes on its actual clause-filter path. Successful under alone does not emit a word: the caller also removes direct Mark children and preserves token order. Its true/false projection cannot determine complete rendered clause text without those caller constraints.

### cost

O(n) per membership call and O(1) extra state. n membership calls per selected clause give O(n²); do not add this to the parent's cubic bound again.

### epoch-memory

The compiled old source panicked while traversing a supplied usize::MAX parent on an unrelated token. Checked parent lookup now terminates false; valid ancestry and non-reaching cycle behavior are preserved. The source-bound fragment selects only the closure, while its executed witness calls the enclosing public API.