Canonical light-cone commutators and their applications.- Local saturation of commutator matrix elements.- Duality in deep inelastic electroproduction.- Parton models of inelastic lepton scattering.- Duality for real and virtual photons.- Scaling in deep inelastic scattering with fixed final states.- Duality and the pion electromagnetic form factor.- Deep inelastic hadronic scattering in dual-resonance model.- Low energy theorems and photo- and electroproduction near threshold by current algebra.