Rudolf Halin
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Rudolf Halin (February 3, 1934 – November 14, 2014) was a German graph theorist, known for defining the ends of infinite graphs,[1] for Halin's grid theorem,[2][3] for extending Menger's theorem to infinite graphs,[4] and for his early research on treewidth and tree decomposition.[5] He is also the namesake of Halin graphs, a class of planar graphs constructed from trees by adding a cycle through the leaves of the given tree; earlier researchers had studied the subclass of cubic Halin graphs but Halin was the first to study this class of graphs in full generality.[6]
Halin was born on February 3, 1934, in Uerdingen.[7] He earned his doctorate from the University of Cologne in 1962, under the supervision of Klaus Wagner and Karl Dörge, after which he joined the faculty of the University of Hamburg.[8] He died on November 14, 2014, in Mölln, Schleswig-Holstein.[7]
