📐algorithm-bk-tree-tests

The groupant beside algorithms/src/bk_tree/tests.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

Components

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.

Model text

descriptant

Exact byte metric BK tree tests

Original std-only Rust implementation and fixtures. Reference: Burkhard and Keller, Some approaches to best-match file searching, CACM 16(4), 1973.

Prospective epoch, 2026-10-30

Domain, recurrence, invariants, costs and validation plan were saved before implementation in $MOVA_DATA/runs/octopus-wave26-indexes-2026-10-30/prospective.md. No runtime gain was predicted or measured.

Executed epoch, 2026-10-30

Two tests: exhaustive_metric_oracle and byte_semantics_and_boundaries.

31 binary byte words of lengths0..4, all31 cyclic insertion orders plus duplicate empty word, all31 queries and radii0,1,2,4,usize::MAX. Independent full2D dynamic programming oracle does not reuse production rolling-row kernel. Explicit255/NUL cases,256-byte and4096-entry boundaries.

Limits

Exact bounded APIs only. No generic 1/2/5/10% accuracy surrogate is supported. Finite tests do not prove universal correctness or runtime gains. Standard Vec/Box/BTreeMap allocation failure may abort or panic; allocator refusal is not injected. No callbacks, I/O or concurrency effects. Partial Rust syntax is source-bound; macro expansion, semantic AST proof and whole-Mova quality remain gaps.

model

Mathematical model

Forward

Execute deterministic fixtures, compare exact API values and state against independent finite oracles, then report success iff all assertions hold. 31 binary byte words of lengths0..4, all31 cyclic insertion orders plus duplicate empty word, all31 queries and radii0,1,2,4,usize::MAX. Independent full2D dynamic programming oracle does not reuse production rolling-row kernel. Explicit255/NUL cases,256-byte and4096-entry boundaries.

Invariant

Fixtures are deterministic, production and oracle observations are compared exactly; state checks inspect parent edges and order where relevant. Assertions fail on disagreement; no benchmark thresholds enter correctness.

Cost

Bounded finite enumeration plus production/oracle work; exhaustive here means the documented small fixture universe only. Runs use ordinary allocator behavior; resource failure is not injected.

behavior_complement

For terminating finite harness executions, reports that disagree with the conjunction of assertions are excluded. Passing a candidate with any fixture mismatch is absent from the specified relation. Abort/nontermination are outside the observation universe; this relation is not a universal production correctness proof.

reverse_reconstruction

A pass admits every implementation agreeing on these finite observations, including implementations differing arbitrarily outside the fixtures. A failure admits production defects or oracle defects; the report alone does not uniquely reconstruct the cause.

oracle_independence

31 binary byte words of lengths0..4, all31 cyclic insertion orders plus duplicate empty word, all31 queries and radii0,1,2,4,usize::MAX. Independent full2D dynamic programming oracle does not reuse production rolling-row kernel. Explicit255/NUL cases,256-byte and4096-entry boundaries.

mutation_sensitivity

Change emission comparison d<=radius to d<radius; exhaustive_metric_oracle must fail. Source bytes are restored before the successful positive rerun. These controls establish sensitivity only to the chosen defects.

finite_schedule

Two tests: exhaustive_metric_oracle and byte_semantics_and_boundaries. Counts and repeat receipts are retained externally; neither repeatability nor test count guarantees unseen behavior.

Gaps

Exact bounded APIs only. No generic 1/2/5/10% accuracy surrogate is supported. Finite tests do not prove universal correctness or runtime gains. Standard Vec/Box/BTreeMap allocation failure may abort or panic; allocator refusal is not injected. No callbacks, I/O or concurrency effects.

evidence

Evidence, 2026-10-30

Four identical normalized runs: 706 tests; 14 new tests. kd_tree: compiled production mutant exit Some(101), named assertion exhaustive_grid_oracle; exact restoration and positive rerun exit Some(0). bk_tree: compiled production mutant exit Some(101), named assertion exhaustive_metric_oracle; exact restoration and positive rerun exit Some(0). interval_tree: compiled production mutant exit Some(101), named assertion exhaustive_closed_overlap_oracle; exact restoration and positive rerun exit Some(0). treap: compiled production mutant exit Some(101), named assertion exhaustive_operation_oracle; exact restoration and positive rerun exit Some(0). splay_tree: compiled production mutant exit Some(101), named assertion exhaustive_stateful_oracle; exact restoration and positive rerun exit Some(0).

Strict mova-algorithms all-target Clippy passed; focused rustfmt passed. Receipts: $MOVA_DATA/runs/octopus-wave26-indexes-2026-10-30. Two freshly generated syntax projections must compare identical before syntax.json installation. No benchmark or training/quality measurement is claimed.

For this module: Two tests: exhaustive_metric_oracle and byte_semantics_and_boundaries.

This page in Markdown → https://md.groupants.elamur.ai/free/en/mova/algorithms/src/bk_tree/tests.rs.groupant/