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Extends the verification harness from sorts-only to the whole repo, and in
doing so surfaces two further latent bugs (on top of the earlier hash-shift one):
Bugs found and fixed:
- queue/elementarypriority.go: max() seeded at the zero value, so an
all-negative queue reported a phantom max of 0 and DeleteMax returned/removed
the wrong element. Caught by the new queue permutation property (testing/quick
generates negatives; the old test data never did). Seed from a[0] instead.
- sort/sleep.go: result built on NewArrayList(len(a)) -- a slice of that LENGTH
(len(a) zeros) -- then appended to, yielding double-length output with leading
zeros. The old .Sorted()-only test passed because zeros-then-ascending is
sorted. Caught by the new Sleep permutation check. Build from an empty slice.
Coverage added:
- queue/property_test.go: ordering + permutation (completeness) for both queues.
- TestSleepSort now also checks permutation, not just Sorted().
- docs/verification.md: paper proofs for all search/set structures (Elementary,
Hash, BST, red-black BST invariants, GoMap) and both priority queues.
- formal/tla/ParallelSort.tla: exhaustive fork/join model of ParallelMerge/
ParallelQuick -- disjoint write-ranges (no data race) + termination. Wired
into make verify-model.
- formal/selection.go: second Gobra proof (memory safety + sortedness). Wired
into make verify-formal.
- docs/case-study-bugs-found.md: extensive write-up of all three bugs, how each
was caught, why the old tests missed it, and the fix (supersedes the earlier
single-bug case study).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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