`BookProof.ChapterA3x.projSym_apply` {N : ℕ} (a b : Idx N) : projSym N a b = (Nat.factorial N : ℂ)⁻¹ * ∑ σ : Equiv.Perm (Fin N), (if b = a ∘ σ then (1 : ℂ) else 0)

Initializing...

`BookProof.ChapterA3x.projSym_apply` {N : ℕ} (a b : Idx N) : projSym N a b = (Nat.factorial N : ℂ)⁻¹ * ∑ σ : Equiv.Perm (Fin N), (if b = a ∘ σ then (1 : ℂ) else 0) · Prove2Me