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Theorems · Theorem · linear algebra

Matrix.trace_permutation

∀ {n : Type u_1} {R : Type u_2} [inst : DecidableEq n] (σ : Equiv.Perm n) [inst_1 : Fintype n]
  [inst_2 : AddCommMonoidWithOne R], (Equiv.Perm.permMatrix R σ).trace = ↑(Function.fixedPoints ⇑σ).ncard

The trace of a permutation matrix equals the number of fixed points.

Defined in
Mathlib.LinearAlgebra.Matrix.Permutation
Cited by
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Foundations
Depth 96 from the axioms · uses propext, Classical.choice, Quot.sound
Assumes
DecidableEqFintypeAddCommMonoidWithOne

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