Formally verified polygon intersection
Opus 4.8 oneshots, prev failed
Details
- External ID
- 48405264
- Source
- HN
- Company
- —
- Product
- Formally verified polygon intersection
- Website domain
- github.com
- Launched
- June 4, 2026
- Cohort
- —
- Upvotes
- 93
- Upvotes percentile
- 0.9105191256830601
- Tags
- —
- Fetched at
- Sept. 7, 2026, 9:26 p.m.
- Updated at
- Sept. 7, 2026, 9:26 p.m.
Description
To my knowledge, this is the first formally verified implementation of an intersection algorithm for polygons.The experience of working with AI agents on this project changed a lot with recent model releases, as I describe in the readme. Opus 4.8 is able to provide algorithm implementation with formal proof in one shot, whereas previous models required me to provide proof strategies in multiple steps.Trust in the correctness comes entirely from the Lean checker and human review of a small specification, not from the LLM.Also check out the web demo built around the verified core linked in the readme: https://schildep.github.io/verified-polygon-intersection/. It supports multipolygons including holes, self intersections, and overlapping edges.
Enrichment
- Theme
- 3d modeling and graphics engines
- Vertical
- Horizontal
- Function
- Dev tools
- Audience
- Developer
- AI stance
- Not AI
- Project type
- Hobby / open-source project
- Normalized one-liner
- formally verified polygon intersection algorithm
- Manually corrected
- False
Could you build this?
No Formal software verification involves interactive theorem provers (like Coq, Lean, or Isabelle) and rigorous mathematical proofs of computational geometry edge cases.
What it would actually take: Requires formal specification in Lean 4 or Coq, encoding geometric topology, floating-point or arbitrary-precision arithmetic proofs, and proving correctness invariants across all degenerate intersection cases. This demands deep expertise in formal methods, computational geometry, and interactive theorem proving.
Discussion
20 comments analyzed.
Competitors mentioned: Video games and GIS systems (existing polygon intersection implementations), Delaunay triangulation libraries, Shewchuk robust predicates
Concerns raised: Real number representation limitations in computer implementation, Floating-point precision issues for computational geometry, Polygon intersection is well-known; unclear what makes this novel, Lack of formal verification library for IEEE floats in Lean (Flocq equivalent)
Feature requests: Extend proof to real coordinates (algebraic numbers like sqrt(2)), Support spline segments instead of just line segments, Formal verification library for floating-point numbers (Flocq-level quality), Extend to 3D polyhedrons with formal verification, Shewchuk robust predicates formally verified library
Competitors
Other products that read as similar to this one — 34 launches clear the similarity bar, closest 8 shown.
Attention rank: #5 of 35 (itself plus its competitors, highest first — normalized so YC and Product Hunt are compared fairly).
Launched 157 days after the earliest competitor.
- Formally verified 3D CSG: Trust 93 lines spec, not 1000 lines AI code · hn · 2026-07-28 · 115 upvotes · similarity 0.62
- genpark-moller-trumbore-3d-ray-triangle-intersection-skill · github · 2026-09-09 · 8 upvotes · similarity 0.39
- genpark-moller-trumbore-3d-ray-triangle-intersection-skill · github · 2026-09-09 · 8 upvotes · similarity 0.39
- c-hd-proof · github · 2026-09-21 · 44 upvotes · similarity 0.39
- Talos · hn · 2026-06-18 · 106 upvotes · similarity 0.37
- genpark-wesolowski-vdf-evaluator-skill · github · 2026-09-10 · 7 upvotes · similarity 0.36
- Sostactic · hn · 2026-04-18 · 14 upvotes · similarity 0.35
- A geometric analysis of Chopin's Prelude No. 4 using 3D topology · hn · 2026-02-20 · 50 upvotes · similarity 0.35
Other launches for this product
- No other launches for this product.
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