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Package reduced-word inversion sequences as Finsets

For a reduced word in a Mathlib CoxeterSystem, add left and right Finset wrappers and prove the two cardinality and two inversion-membership lemmas requested in Langlands issue #47, plus a small finite example.

Why this problem

This is a deliberately bounded 3–5 day student project whose mathematical core has already compiled in isolation. The remaining work is careful packaging, one example, and integration into a serious long-term formalization program.

Verification contract

The issue identifies every Mathlib declaration needed and links a probe in which both definitions and all four core theorems already compile; reproduce that probe, integrate the module, and run repository diagnostics without `sorry`.

Tracking
Difficulty
2/10
Attempts
0
Last attempt
Not yet
Source status
open
External validation
none
Techniques and harnesses
Lean 4Coxeter systemsList.toFinsetreduced-word inversions
Resumable campaign memory

Research map

0 epochs · 0 promising · 0 blocked · 0 ruled out
Next session checkpoint

Select the cheapest new discriminator.

First action: Review the source and strategy registry.

Stop or redirect when: The planned discriminator resolves the route.

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Strategy registry
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Ruled out, with scope
  • Nothing has been rigorously ruled out yet.
Complete history

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