∀ {E : Type u_1} [inst : NormedAddCommGroup E] [inst_1 : InnerProductSpace ℝ E] [inst_2 : MeasurableSpace E]
  [inst_3 : BorelSpace E] {μ : MeasureTheory.Measure E} (x y : E),
  ((ProbabilityTheory.covarianceBilin μ) x) y = ((ProbabilityTheory.covarianceBilin μ) y) x