Elamur Groupantsmath-understand-chunk
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
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 |
| ast | partial | ../syntax.json |
| descriptant | present | descriptant |
| invariant | partial | invariant |
| tests | executed bounded checks | 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 |
reverse_reconstruction | reverse_reconstruction | partial source derived model | reverse_reconstruction |
signed_context | signed_context | partial source derived model | signed_context |
ambiguous_unit_context | ambiguous_unit_context | partial source derived model | ambiguous_unit_context |
Model text
descriptant
math-understand-chunk
read_number builds Rat from digit forms or accumulates number words/multipliers; chunk tries signed/contextual number plus unit before bare unit before word. standins emits placeholder forms with each token mapped to its retained Item index.
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
read_number builds Rat from digit forms or accumulates number words/multipliers; chunk tries signed/contextual number plus unit before bare unit before word. standins emits placeholder forms with each token mapped to its retained Item index.
This source-derived relation is partial; no executable percentage surrogate or replacement is supplied.
invariant
Scoped domain and invariants
Successful number/unit readers advance the consumed token index. Exact Rat/units live in Item, not parser standins. Failed Rat operations may surface as unrecognized lexical material.
Cost
Chunk advances monotonically, but read_number may scan multiword spans and Rat operations have arithmetic costs. standins formatting and output allocation scale with emitted forms.
models
behavior_complement
A recognized fractional word cannot absorb a unit in chunk's number branch. Successful standin emission cannot lose its owner index. Placeholder output does erase sign/unit details, so unique source reconstruction is excluded.
reverse_reconstruction
Items -8 miles and +8 kilograms both emit ['8','units'] with owner[0,0], while retaining different Item values/units. Fractions1/3 and1/2 emit 'half'; placeholder-only preimage is set-valued.
signed_context
A minus is folded into a number only when the previous emitted item is neither Qty nor Unit and the next token starts with an ASCII digit. Otherwise it remains a word/operator token.
ambiguous_unit_context
Bare single-letter scales require to/into/in context; listed ambiguous UnitW abbreviations require a/per/each/every unless after_num=true. Same spelling thus has context-dependent chunk role.
tests
Scoped evidence
Word numbers, fractions, unit ambiguity, speed and negative quantity placeholder ownership.
Named actual source fixtures: understand::wave28::{chunk_units_and_placeholder_transport}.
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.
This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/math/src/understand.rs.groupant/chunk.groupant/