Ain't' mutton! Shephard's lemma is a major result in microeconomics having applications in the theory of the firm and in consumer choice. Slutsky Equation, Roy's Identity and Shephard's Lemma London Disperson Forces... I got your Stirling number of the second kind! Close encounters of the Stirling numbers of the third kind too! Hotelling's law is an observation in economics that in many markets it is rational for producers to make their products as similar as possible. This is also referred to as the principle of minimum differentiation as well as Hotelling's linear city model. Does it go the Manhattan distance in a Random walk? The observation was made by Harold Hotelling (1895–1973) in the article "Stability in Competition" in Economic Journal in 1929.

A fermion is just a particle of half-integer spin. Being a lepton for a particle is a matter of definition of global symmetries of the theory. This means that a lepton can in principle be both a fermion or a boson, although all known leptons are fermions (electron, muon, tau and their neutrinos). The lightest baryon is the proton, and it is the only stable baryon. Since the neutron decays by n --> p + e - + νe and the electron and anti-neutrino are leptons, not baryons, B conservation requires that the neutron is also baryon. Three Laws, Four Basic Forces and Four types of bonds