Elamur Groupantsmath-deduct-transition
The groupant beside math/src/deduct.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 |
self_pair_boundary | self_pair_boundary | partial source derived model | self_pair_boundary |
representative_selection | representative_selection | partial source derived model | representative_selection |
Model text
descriptant
math-deduct-transition
Comb clones state and appends Step, computes selected f64 operation, rejects zero divisor then nonfinite or outside[0,1e12], increments both operand uses and appends a node; Stop appends Step and marks done with pool unchanged.
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
Comb clones state and appends Step, computes selected f64 operation, rejects zero divisor then nonfinite or outside[0,1e12], increments both operand uses and appends a node; Stop appends Step and marks done with pool unchanged.
This source-derived relation is partial; no executable percentage surrogate or replacement is supplied.
invariant
Scoped domain and invariants
Valid operand/feature indices and bounded uses counters are required. Old pool nodes remain and pool grows exactly1 on successful Comb; Stop retains pool size.
Cost
Every attempt clones pool/tree state before numerical rejection. Accepted Comb additionally clones operand trees and builds canonical key strings; rejected arithmetic is not allocation-free.
models
behavior_complement
Successful Comb cannot contain a new negative, nonfinite or>1e12 value under valid indices. Stop cannot append a numeric node. apply does not exclude equal operand indices even though cands does.
reverse_reconstruction
Last value5 is compatible with8-3 or10/2, so the scalar cannot identify operands. Full resulting state plus its last Step preserves original pool and selected indices, narrowing reconstruction; use counters may still require bounded/no-overflow assumptions.
self_pair_boundary
apply(Comb(i,i,Mul)) can succeed and increments that node's uses twice. cands enumerates only i!=j; gold acceptance and direct apply success therefore do not establish search reachability.
representative_selection
New representative=a.rep when a is a leaf and b is not; otherwise b.rep. This differs from steps' max-text-index representative and affects feature transport.
tests
Scoped evidence
Private actual apply/cands: divide0, negative, upper bound, legal difference, no candidate self-pair and Stop availability.
Named actual source fixtures: deduct::wave28::{numeric_transition_boundary}.
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/deduct.rs.groupant/transition.groupant/