... no continuous trajectories on a lattice and, hence, no true path integrals in this case.But since in quantum mechanics as well as in quantum field theory the precise definition of a path integralis ... application of path integrals in quantum mechanics, also considered in chapter 2, is thestudy of systems with topological constraints, e.g., a particle moving in some restricted domain of theentire ... motion were developed in the pioneering work by A Einstein (1905, 1906) (these fundamental works on Brownian motionwere reprinted in Einstein (1926, 1956)).12Brownian motion: introduction to the...