{"slug": "hol-light", "name": "HOL Light", "category": "other", "category_name": "Other software", "description": "", "recommenders": 3, "commenters": 3, "warners": 0, "score": 2.587, "rising": 0.35, "first": "2025-11-07", "latest": "2026-08-04", "why": "The HOL Light kernel (mentioned in the article) is about 500 lines from one file", "why_is_quote": true, "has_verdict": false, "sentiment": {"recommend": 3, "neutral": 1, "compare": 0, "warn": 0}, "spark": [1, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0], "listed": true, "loved": [], "caveat": "", "short_quote": "The HOL Light kernel (mentioned in the article) is about 500 lines from one file", "kind": "", "icon": true, "domain": null, "github_repo": "github.com/jrh13/hol-light", "official_url": "https://hol-light.github.io", "pricing": "", "aliases": ["HOL Light", "HOL-Light"], "verdict": null, "praise": [{"label": "", "summary": "", "quotes": [{"id": 786868512, "item_id": 49179282, "url": "https://news.ycombinator.com/item?id=49179282", "by": "momentoftop", "date": "2026-08-04", "version": null, "stance": "recommend", "quote": "The HOL Light kernel (mentioned in the article) is about 500 lines from one file", "excerpt": "Pretty much. The kernel of a proof assistant is the absolutely trusted core, and ultimately gets to decide what is or isn't a proven mathematical fact (so roughly a kernel resource). Over that, you build a huge amount of (userspace) tooling that doesn't have to be absolutely trusted since its job is just to talk into the kernel and get theorems. A kernel bug manifests as the kernel deciding that something is a theore", "context": "", "use_case": "", "switched_from": "", "story": "Why is it all in the kernel?"}, {"id": 750234768, "item_id": 46889673, "url": "https://news.ycombinator.com/item?id=46889673", "by": "GregarianChild", "date": "2026-02-04", "version": null, "stance": "recommend", "quote": "A mere 676 LoCs.", "excerpt": "This is wrong as the others replies also point out. Tactics in LCF-style provers are not part of the TCB. Here is an example of the TCB for an industrial strength prover: \u25cb https://github.com/jrh13/hol-light/blob/master/fusion.ml A mere 676 LoCs. This miniscule size of the TCB is where the comparatively lesser bug count (despite intense use) comes from.", "context": "", "use_case": "", "switched_from": "", "story": "Broken Proofs and Broken Provers"}, {"id": 733611649, "item_id": 45850728, "url": "https://news.ycombinator.com/item?id=45850728", "by": "specialgoodness", "date": "2025-11-07", "version": null, "stance": "recommend", "quote": "Don't forget the amazing theorem provers too", "excerpt": "Xavier Leroy as Lou Reed... :-) Don't forget the amazing theorem provers too, like Imandra ( https://www.imandra.ai/core ), HOL-Light ( https://hol-light.github.io/ ) and Rocq ( https://rocq-prover.org/ ), ... !", "context": "", "use_case": "", "switched_from": "", "story": "Why I love OCaml (2023)"}]}], "caveats": [], "who": [{"by": "momentoftop", "context": "formal verification researcher", "url": "https://news.ycombinator.com/item?id=49065741", "date": "2026-07-26"}], "tags": [], "use_cases": ["formal verification"], "compared": [{"slug": "rocq", "name": "Rocq", "co": 2, "switched_from": 0, "switched_to": 0}], "makers": [], "threads": [{"url": "https://news.ycombinator.com/item?id=49123231", "title": "Why is it all in the kernel?", "mentions": 1}, {"url": "https://news.ycombinator.com/item?id=49062291", "title": "We have proof automation now", "mentions": 1}, {"url": "https://news.ycombinator.com/item?id=46883337", "title": "Broken Proofs and Broken Provers", "mentions": 1}, {"url": "https://news.ycombinator.com/item?id=45846517", "title": "Why I love OCaml (2023)", "mentions": 1}], "sentiment_by_month": {"2025-11": {"recommend": 1}, "2025-12": {}, "2026-01": {}, "2026-02": {"recommend": 1}, "2026-03": {}, "2026-04": {}, "2026-05": {}, "2026-06": {}, "2026-07": {"neutral": 1}, "2026-08": {"recommend": 1}, "2026-09": {}, "2026-10": {}}, "versions": [], "version_unnamed": 0, "family_ref": null, "runs_on": null, "lines": [], "quotes": [{"id": 786868512, "item_id": 49179282, "url": "https://news.ycombinator.com/item?id=49179282", "by": "momentoftop", "date": "2026-08-04", "version": null, "stance": "recommend", "quote": "The HOL Light kernel (mentioned in the article) is about 500 lines from one file", "excerpt": "Pretty much. The kernel of a proof assistant is the absolutely trusted core, and ultimately gets to decide what is or isn't a proven mathematical fact (so roughly a kernel resource). Over that, you build a huge amount of (userspace) tooling that doesn't have to be absolutely trusted since its job is just to talk into the kernel and get theorems. A kernel bug manifests as the kernel deciding that something is a theore", "context": "", "use_case": "", "switched_from": "", "story": "Why is it all in the kernel?"}, {"id": 785051856, "item_id": 49065741, "url": "https://news.ycombinator.com/item?id=49065741", "by": "momentoftop", "date": "2026-07-26", "version": null, "stance": "neutral", "quote": "I used HOL Light about 15 years ago.", "excerpt": "Theorem provers have always made extensive use of AI and automation. Formal logic is insanely laborious, and it took Russell a monumental effort to not get very far with his manual verifications in Principia Mathematica, working out all the details by hand. In 1956, Newell came up with the Logic Theorist which was able to prove a decent chunk of the Principia automatically. When Newell informed him, Russell conceded ", "context": "formal verification researcher", "use_case": "formal verification", "switched_from": "", "story": "We have proof automation now"}, {"id": 750234768, "item_id": 46889673, "url": "https://news.ycombinator.com/item?id=46889673", "by": "GregarianChild", "date": "2026-02-04", "version": null, "stance": "recommend", "quote": "A mere 676 LoCs.", "excerpt": "This is wrong as the others replies also point out. Tactics in LCF-style provers are not part of the TCB. Here is an example of the TCB for an industrial strength prover: \u25cb https://github.com/jrh13/hol-light/blob/master/fusion.ml A mere 676 LoCs. This miniscule size of the TCB is where the comparatively lesser bug count (despite intense use) comes from.", "context": "", "use_case": "", "switched_from": "", "story": "Broken Proofs and Broken Provers"}, {"id": 733611649, "item_id": 45850728, "url": "https://news.ycombinator.com/item?id=45850728", "by": "specialgoodness", "date": "2025-11-07", "version": null, "stance": "recommend", "quote": "Don't forget the amazing theorem provers too", "excerpt": "Xavier Leroy as Lou Reed... :-) Don't forget the amazing theorem provers too, like Imandra ( https://www.imandra.ai/core ), HOL-Light ( https://hol-light.github.io/ ) and Rocq ( https://rocq-prover.org/ ), ... !", "context": "", "use_case": "", "switched_from": "", "story": "Why I love OCaml (2023)"}]}