Quark fragmentation functions in hadronic and deep inelastic single particle inclusive processes

In the framework of Feymann's quark-parton model for inclusive electroproduction and quark model of Ezawa, Maharana and Miyazawa for hadronic inclusive processes, relations between invariant cross sections for electroproduction of ppions and purely hadronic production of pions in the beam fragmentation regions are derived. They are satisfied by data. The ratio of parton fragmentation functions is estimated from purely hadronic processes independently from the parton model. (author)