2 Diffusion OperatorscircleSection 2.1: Self-Adjoint OperatorscircleSection 2.2: Diffusion OperatorscircleSection 2.3: The Heat SemigroupcircleSection 2.4: The Submarkov PropertycircleSection 2.5: InterpolationscircleSection 2.6: The Hille-Yosida TheoremcircleSection 2.7: Solution of the Cauchy ProblemPowered by Spec