Haim Hanani

Haim Hanani (* as Chaim Chojnacki on September 11, 1912 in Slupca ; † April 1991 ) was an Israeli-Polish mathematician who dealt with combinatorics .

Hanani studied mathematics at the Universities of Vienna and Warsaw, graduating in Warsaw in 1934. In 1935 he went to Palestine and was the first to receive a doctorate in mathematics at the Hebrew University in 1938. He fought for the independence of Israel in the Hagana and was therefore imprisoned by the British. In 1955 he became a professor at the Technion . 1969 to 1973 he was the first rector of Ben Gurion University in the Negev .

He has published with Paul Erdős , Alexander Schrijver , Richard M. Wilson and Andries Brouwer . Hanani-Tutte's theorem in graph theory is named after him and William Thomas Tutte , with Hanani’s contribution from 1934 (who proved it for two minimal non-planar graphs) and Tutte’s 1970 (general case) contribution: A Graph is planar if and only if there is a graph drawing in which every pair of independent edges (i.e. without common endpoints) do not intersect at all or have an even number of intersection points.

He is also known for his work on block plans , especially Pairwise Balanced Designs (PBD). In 1960 he gave a constructive proof of the existence of Steiner quadruple systems with points for all with . ${\displaystyle n}$ ${\displaystyle n\equiv 2{\text{ oder }}4{\pmod {6}}}$ ${\displaystyle n>2}$

Web links

• Roman Duda, Emigration of mathematicians from Poland in the 20th century, pdf

Individual evidence

1. ↑ Chojnacki, On essentially unsmoothed curves in three-dimensional space, Fundamenta Mathematicae, 23, 1934, 135–142
2. ^ Tutte, Toward a theory of crossing numbers, Journal of Combinatorial Theory 8, 1970, 45-53
3. ↑ Steiner Quadruple Systems, Sage
4. ↑ Hanani, On quadruple systems, Canadian Journal of Mathematics, 12, 1960, 145-157