Helmut Hasse

The graph, which describes a particular poset, is called a Hasse diagram after the 20- century German mathematician Helmut Hasse (1898-1979) (Rosen 1991). See also chapter by Halfon p. 385. 

As far as we can tell, the use of partial order in environmental systems started with the contributions of Halfon. We do not presume to write a competent chapter about the historical development of partial order in chemistry and in environmental sciences. However, in the proceeding chapter Halfon gives his view on the development of divers programs within the context of Hasse diagrams. The chapter shows the influence of Helmut Hasse, the important steps done by the Italian scientists Reggiani and Marchetti and the developments done by Halfon and in the period since 1986. 

A literature review led Halfon to the field of research where Reggiani and Marchetti (1975) were active. Both engineers worked at Selenia, an industrial electronics company in Rome, Italy. Their approach was based on earlier research done a by Helmut Hasse during the 1940 s and the early 1950 s. Collaboration with Dr. Reggiani that lasted several years (Halfon and Reggiani 1978, Reggiani and Halfon 1979, Halfon and Reggiani 1986). Dr. Marchetti, a student at the time, moved on to other research endeavours. 

Leopoldt HW (1982) Obituary Helmut Hasse (August 25, 1898-December 26, 1979). J Number Theory 14(1) 118-120... 

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