`BookProof.QuantumGravityBrstCharge.linGen_contract_left` (A B : Matrix (Fin d) (Fin d) ℝ) : (∑ j, ∑ k, ∑ l, ∑ m, (A j k * B l m) • (if k = l then elemGen j m else 0)) = linGen (A

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`BookProof.QuantumGravityBrstCharge.linGen_contract_left` (A B : Matrix (Fin d) (Fin d) ℝ) : (∑ j, ∑ k, ∑ l, ∑ m, (A j k * B l m) • (if k = l then elemGen j m else 0)) = linGen (A · Prove2Me