leanprover-community

mathlib4

Lean2023–2026

leanprover-community / mathlib4

mathlib4

The math library of Lean 4

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18Distinct people

20Mentions

1Explicit recommenders

4.5KGitHub stars

REPOSITORY AT A GLANCE

What to know before exploring

What it is

The math library of Lean 4

GitHub

Where it is used

No documented product use was verified in the last source check.

What people are saying

I may have been spending too much time with Lean recently, but the number one thing I’d like to see for the future of TLA+ is an equivalent of Mathlib…

mjb used a recommendation phrase. One indexed comment matches. This is a phrase match, not a verdict.

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Also in these discussions

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This week on Hacker News

Nov 8–Nov 15 UTC · Direct repository links and separately labeled related project stories. Indexed through 11/15/2026, 2:17:07 AM UTC.

No direct repository links were found in the indexed HN discussions over the past seven days. Older discussions are available below.

Mentions over time

HN mentions by year20 dated mentions

Observed mentions: 2023-09-08 09:05:46 UTC to 2026-10-07 16:34:54 UTC.

* An incomplete calendar period is marked with an outlined bar. Its count is not directly comparable with a full period.

Counts come from the repository’s dated source evidence. Index cutoff: 2026-11-02 08:16:59 UTC.

View mention counts and date ranges

UTC ranges include their start and exclude their end. Select a period to filter the source evidence.
Period	Start (UTC)	End (exclusive, UTC)	Mentions	Submissions	Comments
2023	2023-01-01 00:00:00 UTC	2024-01-01 00:00:00 UTC	8	0	8
2024	2024-01-01 00:00:00 UTC	2025-01-01 00:00:00 UTC	5	0	5
2025	2025-01-01 00:00:00 UTC	2026-01-01 00:00:00 UTC	5	1	4
2026 (partial)	2026-01-01 00:00:00 UTC	2027-01-01 00:00:00 UTC	2	0	2

What Hacker News says

8 sources

kmill·Nov 6, 2023

We essentially implemented this matrix version in Lean/mathlib to both compute the fibonacci number and generate an efficient proof for the calculation. https://github.com/leanprover-community/mathlib4/blob/master... In practice this isn't very useful (the definition of Nat.fib unfolds quick enough and concrete large fibonacci numbers don't often appear in proofs) but still it shaves a bit of time off the calculation and the proof verification.

In A linear algebra trick for computing Fibonacci numbers fast

westurner·Nov 1, 2023

https://en.wikipedia.org/wiki/Zermelo%E2%80%93Fraenkel_set_t... : > Today, Zermelo–Fraenkel set theory [ZFC], with the historically controversial axiom of choice (AC) included, is the standard form of axiomatic set theory and as such is the most common foundation of mathematics. Foundation of mathematics: https://en.wikipedia.org/wiki/Foundations_of_mathematics Implementation of mathematics in set theory: https://en.wikipedia.org/wiki/Implementation_of_mathematics_... : > The implementation of a number of basic mathematical concepts is carried out in parallel in ZFC (the dominant set theory) and in NFU, the version of Quine's New Foundations shown to be consistent by R. B. Jensen in 1969 (here understood to include at least axioms of Infinity and Choice). > What is said here applies also to two families of set theories: on the one hand, a

Read the rest

range of theories including Zermelo set theory near the lower end of the scale and going up to ZFC extended with large cardinal hypotheses such as "there is a measurable cardinal"; and on the other hand a hierarchy of extensions of NFU which is surveyed in the New Foundations article. These correspond to different general views of what the set-theoretical universe is like IEEE-754 specifies that float64s have ±infinity and specify ZeroDivisionError. Symbolic CAS with MPFR needn't be limited to float64s. HoTT in CoQ: Coq-HoTT: https://github.com/HoTT/Coq-HoTT What is the relation between Coq-HoTT & Homotopy Type Theory and Set Theory with e.g. ZFC? Homotopy Type Theory: https://en.wikipedia.org/wiki/Homotopy_type_theory : > "Cartesian Cubical Computational Type Theory: Constructive Reasoning with Paths and Equalities" (2018) https://scholar.google.com/scholar?cites=9763697449338277760... and sorted by date: https://scholar.google.com/scholar?hl=en&as_sdt=5,43&sciodt=... What does Mathlib have for SetTheory, ZFC, NFU, and HoTT? leanprover-community/mathlib4// Mathlib/SetTheory: https://github.com/leanprover-community/mathlib4/tree/master...

In What do we mean by "the foundations of mathematics"?

Smaug123·Sep 20, 2023

As an aside, there are a number of Turing machines defined in Lean's mathlib. https://github.com/leanprover-community/mathlib4/blob/2c3ee3...

In Show HN: A reference implementation of Turing's paper “On Computable Numbers”

hackandthink·Sep 8, 2023

Thanks, and there is Subobject, which looks like the subobject classifier. https://github.com/leanprover-community/mathlib4/blob/master...

In Lean 4.0

hiker·Sep 8, 2023

There are definitions for sheaves, Grothendieck topologies and sites[1] which were extensively used in the Liquid Tensor Experiment[2] [1] https://github.com/leanprover-community/mathlib4/tree/master... [2] https://leanprover-community.github.io/blog/posts/lte-final/

In Lean 4.0

hackandthink·Sep 8, 2023

Is Lean a Category? (like much debated: is Hask(ell) a Category) "In this section we set up the theory so that Lean's types and functions between them can be viewed as a `LargeCategory` in our framework." So it seems to be proven that there is a Category Lean! https://github.com/leanprover-community/mathlib4/blob/master...

In Lean 4.0

hackandthink·Sep 8, 2023

Everything I can think of and more of what I'll ever need: https://github.com/leanprover-community/mathlib4/tree/master...

In Lean 4.0

mauricioc·Sep 8, 2023

Mathlib was fully ported to Lean 4 (https://github.com/leanprover-community/mathlib4), and the Lean 3 version is deprecated now. Edit: Adding a little bit more detail, it was ported one file at a time, using the automated translation from mathport (https://github.com/leanprover-community/mathport) as a starting point.

In Lean 4.0