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

The groupant beside world/src/span.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/span.rs`](https://github.com/ElamurAI/mova-free/blob/main/world/src/span.rs)
- **source SHA-256:** `4d215ccd57884f41…`
- **covers:** Source scope beginning pub fn find_pred(t: &Tree, preds: &[String]) -> Option<usize> {; selected node envelope, partial semantic coverage. (bytes 6396–7077)
- **part of:** [answer-span](https://md.groupants.elamur.ai/free/en/mova/world/src/span.rs.groupant/)
- **repository folder:** [`world/src/span.rs.groupant/predicate.groupant`](https://github.com/ElamurAI/mova-free/tree/main/world/src/span.rs.groupant/predicate.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` |
| **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 |
|---|---|---|---|
| `answer-span-predicate-behavior-complement` | behavior_complement | partial source model | [behavior-complement](#behavior-complement) |
| `answer-span-predicate-reverse-reconstruction` | reverse_reconstruction | partial source model | [reverse-reconstruction](#reverse-reconstruction) |
| `answer-span-predicate-lexical-rank` | priority_relation | partial source model | [lexical-rank](#lexical-rank) |
| `answer-span-predicate-suffix-equivalence` | information_loss | partial source model | [suffix-equivalence](#suffix-equivalence) |
| `answer-span-predicate-finite-rank-fibers` | reverse_reconstruction | bounded native correspondence | [finite-rank-fibers](#finite-rank-fibers) |

## Model text


### model

## answer-span-predicate

Subject: world/src/span.rs, whole-file SHA-256 in manifest, baseline 4279da541. Domain: finite acyclic valid trees with consistent child lists, valid indices and terminating dependencies. Observation: a single call return, not semantic truth or reachability. Hold Tree, ans::lemmas and types::FEELING dependencies fixed; parser/model loading and external caller wiring are gaps. All entries are source-derived partial models. Exact-target definitions are not executable inverses; finite tests cannot establish universal correspondence.

### forward

Scan caller predicates then token ranks; return first admissible minimum.

### invariant

Tie keeps earliest token; PROPN has rank 3.

### cost

O(p*n*L) with opaque morphology allocations.

### epoch-memory

2026-10-29: initial source-bound epoch. Preserve Num bypass, global Feel selection, early-return cleanup suppression, and verb_kids comment mismatch: code expands Xcomp only and checks no shared subject. No source changes or task-accuracy claim. Partial syntax has no semantic analysis or macro expansion.

### checks

Structural inventory checks hashes, references, types and node bounds only. Proposed oracle: enumerate small annotated acyclic trees and compare literal expected returns, including None and labels; mutate priority or echo inequality to obtain a red control. Any executed bounded evidence is recorded separately in root evidence.md; catalog examples remain proposed until recorded there.

### composition

Leaf scope shares immutable tree/question/helper contracts. Overlap with parent is not extra runtime work. Dependencies outside range remain opaque.

### behavior-complement

U=(Tree,preds) x Option<index>; R=find_pred. Inner U minus R excludes out-of-range outputs, rank-3 outputs and later equal-rank hits when earlier hits exist for first admissible predicate.

Assumptions/evidence/status: common domain above; source-derived partial relation at bound revision. Approximation and held-fixed inputs are stated in the relation. Oracle: finite literal fixtures exercising both membership and nonmembership against the actual function, preserving ambiguous preimages. No linguistic correctness or universal proof inferred.

### reverse-reconstruction

For Some(i), retain all lists with a first admissible predicate whose minimum (rank,index) hit is i; preceding entries may match only rank 3. None includes empty lists, no hits and rank-3-only hits. Morphology ambiguity remains.

Assumptions/evidence/status: common domain above; source-derived partial relation at bound revision. Approximation and held-fixed inputs are stated in the relation. Oracle: finite literal fixtures exercising both membership and nonmembership against the actual function, preserving ambiguous preimages. No linguistic correctness or universal proof inferred.

### lexical-rank

Fixed predicate and hit set: choose minimum (rank,index), requiring rank<3. Hit means equal lemma, equal form or ans::lemmas(form) membership. Changing POS can change winner without changing spelling.

Assumptions/evidence/status: common domain above; source-derived partial relation at bound revision. Approximation and held-fixed inputs are stated in the relation. Oracle: finite literal fixtures exercising both membership and nonmembership against the actual function, preserving ambiguous preimages. No linguistic correctness or universal proof inferred.

### suffix-equivalence

Any preds suffix after first accepted predicate is unobserved. Inserting predicates having no admissible matches before it preserves output. This is a sufficient equivalence family, not exhaustive.

Assumptions/evidence/status: common domain above; source-derived partial relation at bound revision. Approximation and held-fixed inputs are stated in the relation. Oracle: finite literal fixtures exercising both membership and nonmembership against the actual function, preserving ambiguous preimages. No linguistic correctness or universal proof inferred.

### wave6

## Native selection observations, 2026-10-30

Revision: exact source SHA in this manifest. Observations are single terminating calls. Tree fixtures are directly annotated, acyclic and index-valid; dependencies are compiled from this checkout. No parser or teacher is loaded. Metric is exact equality of optional indices/text and rule labels; zero tolerance. Exhaustive claims apply only to explicitly bounded domains, with no semantic accuracy or general Rust proof.

### finite-rank-fibers

Fix three forms/lemmas to ruby, preds=[ruby], rank tags {VERB,ADJ,NOUN,PROPN}. Domain is all 4^3=64 rank triples. A(r)=argmin (r_i,i) among r_i<3, or None if empty. B(j) contains every triple with r_j<3, each earlier rank strictly larger and each later rank at least r_j; B(None)={(3,3,3)}. The native test enumerates entire actual and oracle maps of fibers and compares equality, including earliest ties. This is complete for this finite tag set; AUX and morphology are outside the enumeration. Two additional literal caller-order observations show an earlier predicate noun outranks a later predicate verb. Test predicate_rank_complete_fibers_and_caller_order.