Hans Blichfeldt
Hans Frederik Blichfeldt (also Hans Frederick Blichfeldt, born January 9, 1873 in Illar in Denmark , † November 16, 1945 in Palo Alto ) was an American mathematician who dealt with group theory and number theory.
Live and act
Hans Blichfeldt emigrated with his parents from Denmark to the USA in 1888, where he worked as a farm worker and in sawmills and finally as a traveling surveyor, who was known to his colleagues for his excellent mental arithmetic skills. His mathematical talent was already noticed as a child and he passed the entrance exams for the university in Denmark with distinction, but he was only able to study in the USA at a relatively advanced age from 1894 at Stanford University . After graduating in 1897, he went (with money borrowed from one of his Stanford professors) to the University of Leipzig , where he received his doctorate with Sophus Lie with a thesis on transformation groups. He then returned to Stanford, where he was instructor from 1898 and professor from 1913 until his retirement in 1938, from 1927 as chairman of the mathematics department. In 1911 he was visiting professor at the University of Chicago and in 1924/5 at Columbia University .
Blichfeldt dealt with the geometry of numbers (where Blichfeldt's principle - also the Blichfeldt theorem - is named after him and where he gave precise estimates for the minima of positively definite quadratic forms in 6, 7 and 8 variables), but is mainly through two Books on finite groups known. He classified all finite collineation groups into four variables. His work on square shapes has applications in determining the closest lattice packing of spheres. In 1934 he found the densest such packings in dimensions 6, 7 and 8 (in higher dimensions the question is still unsolved today).
In 1912 he was Vice President of the American Mathematical Society , and in 1920 he was elected to the National Academy of Sciences . In 1938 he received the Dannebrog Order .
Fonts
- A new principle in the geometry of numbers with some applications , Transact. AMS 15 (1914), pp. 227-235
- with George Abram Miller , Leonard Dickson : Theory and Application of Finite Groups , New York, Wiley 1916, Reprint Dover 1961
- Finite Collineation Groups , University of Chicago Press 1917
- The minimum values of positive quadratic forms in six, seven and eight variables , Math. Z. 39 (1935), pp. 1–15 online, PDF file
literature
- Gottwald, Illgauds, Schlote Lexicon of Important Mathematicians , 1990
Web links
- John J. O'Connor, Edmund F. Robertson : Hans Blichfeldt. In: MacTutor History of Mathematics archive .
- Obituary in Stanford (PDF; 13 kB)
- Literature by and about Hans Blichfeldt in the bibliographic database WorldCat
Individual evidence
- ↑ Eric Weis stone HyperSphere packings, tungsten Mathworld
- ^ Blichfeldt, The Minimum Value of Positive Quadratic Forms in Six, Seven, and Eight Variables, Math. Zeitschrift, Volume 39, 1934, pp. 1-15
| personal data | |
|---|---|
| SURNAME | Blichfeldt, Hans |
| ALTERNATIVE NAMES | Blichfeldt, Hans Frederik; Blichfeldt, Hans Frederick; Blichfeldt, Hans F. |
| BRIEF DESCRIPTION | American mathematician |
| DATE OF BIRTH | January 9, 1873 |
| PLACE OF BIRTH | Illar , Denmark |
| DATE OF DEATH | November 16, 1945 |
| Place of death | Palo Alto |