[Merged by Bors] - feat(combinatorics/young): define list of row lengths of a Young diagram #17061
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| -- This belongs somewhere in the list namespace. Is it already in mathlib? |
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Probably the best would be in data/list/range.lean, but if list.sorted isn't avaliable there, perhaps put these in data/list/sort.lean?
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Found it: there is list.pairwise_lt_range but no list.pairwise_le_range. Adding it seems to mean all of mathlib has to be recompiled (since list is so basic). Is there a way to speed it up?
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You can make the change, then push a commit to your branch; CI will run on it, and when it is done you can use leanproject get-cache to download the compiled oleans.
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Co-authored-by: Kyle Miller <kmill31415@gmail.com>
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…ram (#17061) Define `row_lens : list ℕ`, the list of row lengths of a Young diagram and prove it is weakly decreasing and positive. This is the first half of the equivalence `young_diagram ≃ {w : list ℕ // w.sorted (≥) ∧ ∀ x ∈ w, 0 < x}`.
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Define
row_lens : list ℕ, the list of row lengths of a Young diagram and prove it is weakly decreasing and positive.This is the first half of the equivalence
young_diagram ≃ {w : list ℕ // w.sorted (≥) ∧ ∀ x ∈ w, 0 < x}.The rest of the equivalence will be established in a separate PR.
The fact that
list.range nis a sorted list seems worth having in mathlib but I'm not sure where it would go. In thelistnamespace?