`BookProof.LorentzGroup.delta_card_four` : ({1, eta, -eta, -1} : Finset (Matrix (Fin 4) (Fin 4) ℝ)).card = 4

Proved

BookProof.LorentzGroup.delta_card_four

by leonardopedro · Oct 9, 2026 · Mathlib 0df444a (Lean v4.33.1)

theoremstimepiece

Prove the following Lean 4 theorem from ChapterLorentzGroup.

BookProof.LorentzGroup.delta_card_four : ({1, eta, -eta, -1} : Finset (Matrix (Fin 4) (Fin 4) ℝ)).card = 4

Formalization note: Lean 4 identifier BookProof.LorentzGroup.delta_card_four.

Preamble

-- Generated from ChapterLorentzGroup.lean — theorem BookProof.LorentzGroup.delta_card_four
import Mathlib
import Definitions.Def_ChapterLorentzGroup
open BookProof.LorentzGroup



open Matrix

Formal statement

theorem BookProof.LorentzGroup.delta_card_four :
    ({1, eta, -eta, -1} : Finset (Matrix (Fin 4) (Fin 4) ℝ)).card = 4 := by sorry

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