📐algorithm-treap-tests

The groupant beside algorithms/src/treap/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

Explicit-priority bounded treap tests

Original std-only Rust implementation and fixtures. Reference: Seidel and Aragon, Randomized Search Trees, Algorithmica 16, 1996.

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_operation_oracle and priorities_capacity_and_reuse.

All46656 six-step operation schedules over insert/remove of three keys, alternating explicit priorities; compare to BTreeSet after each step and independently check BST bounds, heap, parent pointers, reachability and free-list partition. Capacity4096, linear-height priorities, reuse after2048 deletions, ties and integer extrema.

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. All46656 six-step operation schedules over insert/remove of three keys, alternating explicit priorities; compare to BTreeSet after each step and independently check BST bounds, heap, parent pointers, reachability and free-list partition. Capacity4096, linear-height priorities, reuse after2048 deletions, ties and integer extrema.

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

All46656 six-step operation schedules over insert/remove of three keys, alternating explicit priorities; compare to BTreeSet after each step and independently check BST bounds, heap, parent pointers, reachability and free-list partition. Capacity4096, linear-height priorities, reuse after2048 deletions, ties and integer extrema.

mutation_sensitivity

Negate public contains result; exhaustive_operation_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_operation_oracle and priorities_capacity_and_reuse. 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_operation_oracle and priorities_capacity_and_reuse.

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