Oh this is great! I always have this problem. I find that's one of my biggest barriers when reading queueing theory content. I'm only doing it intermittently so

Oh this is great! I always have this problem. I find that's one of my biggest barriers when reading queueing theory content. I'm only doing it intermittently so I don't have memorized the meanings of ρ,σ,μ,λ... Visually I also often confuse rho and sigma, and math texts will use psi ψ and phi φ in weird fonts and I can never tell them apart.