Contests.lean`

Explanation legend Lean4 Domain Explanation Language (L4DEL)

L4DEL explanations are a separate layer. They do not change the Lean source. Intuition is explanatory prose; numbered items are a reading path; sources link the wording back to evidence.

L4DEL: Lean4 Domain Explanation Language

Annotation provenance. This overlay contains 8 curated AI-written annotations and 3305 mechanical source-derived annotations. They have not been human-reviewed as explanations; treat them as unverified and not mathematical authority. Retained generation history: The 71 original curated annotations were produced in a Claude Sonnet 5.5 session at medium effort; Claude Opus 5.5 is recorded in that session as the advisor model, not the direct author. The bulk source-derived expansion was generated mechanically from pinned source comments by tooling developed in a GPT-5.6 Sol session at ultra reasoning; GPT-5.6 Sol did not originate the quoted source prose. On 2026-10-17 the mechanically generated source-comment annotations of the Formal Conjectures, Carleson, FLT, PFR, CompFiles, Mathematics in Lean and Theorem Proving in Lean overlays were regenerated by the same generator after three corrections made in a Claude Sonnet 5.5 session: titles no longer cut a sentence inside mathematics or end on a dangling word, workflow markers are removed from the quoted prose, and declaration names follow the scanner's namespace resolution. The boilerplate step line was dropped, and comments that were only a row of dashes no longer yield annotations. No new prose was written and no human review is claimed.

Credit: The upstream authors and contributors retain credit for the project and mathematics. lean4-explainer only renders their pinned source and adds the separately disclosed explanation layer.

Project sources: Pinned compfiles documentation, Pinned compfiles corpus index

8 declarations, 0 contain sorry, 0 declared as axioms

Contest Metadata

Data and identification utilities for each contest (IMO, USAMO, etc.). To add a new contest, define a new Contest instance and add it to allContests.

Imports (3)

Imported by 6 files

abbrev ContestIndex Index for identifying individual problems within a contest line 18 source
Source documentation
Index for identifying individual problems within a contest. Currently Nat × Nat covers (year, problemNum) and (day, problemNum).
```
abbrev ContestIndex := Nat × Nat
```
structure WriteupLink A link to an external resource (solution writeup, official site, etc.) line 21 source
Source documentation
A link to an external resource (solution writeup, official site, etc.).
```
structure WriteupLink where
…
```
structure Contest line 26 source
def Contest.filterProblemCount line 46 source
def Contest.problemCount All problems listed (including not yet formalized ones) line 52 source
Source documentation
All problems listed (including not yet formalized ones)
```
def problemCount (c : Contest idx subIdx) : Nat := c.filterProblemCount fun _ _ => true
```
Mentions: Contest
def Contest.hasProblemName line 54 source
def Contest.mergeNeighbors line 57 source
def fromCounts line 72 source