# Helmut Alt

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German computer scientist

**Helmut Alt** (born 1950) is a German computer scientist whose research concerns [graph algorithms](/source/Graph_algorithm) and [computational geometry](/source/Computational_geometry). He is known for his work on matching geometric shapes, including methods for efficiently computing the [Fréchet distance](/source/Fr%C3%A9chet_distance) between shapes. He was also the first to use the German phrase "Algorithmische Geometrie" [algorithmic geometry] to refer to [computational geometry](/source/Computational_geometry).[1] He is a professor of computer science at the [Free University of Berlin](/source/Free_University_of_Berlin).[2]

## Education and career

Alt was born in 1950 in Wolfersweiler, a town in [Saarland](/source/Saarland) that later became incorporated into [Nohfelden](/source/Nohfelden).[1] He became a student of [Kurt Mehlhorn](/source/Kurt_Mehlhorn) at [Saarland University](/source/Saarland_University), where he completed his Ph.D. in 1976 on algorithms for parsing [context-free languages](/source/Context-free_language).[3]

At the Free University of Berlin, he became the doctoral advisor of many successful students,[1] including [Otfried Cheong](/source/Otfried_Cheong) (1992), Johannes Blömer (1993), Christian Knauer (2002), [Carola Wenk](/source/Carola_Wenk) (2002), and [Maike Buchin](/source/Maike_Buchin) (2007).[3]

## Recognition

The Free University of Berlin held a symposium on 2015 in honor of Alt's 65th birthday.[4] Another symposium in honor of Alt and Günter Rote was held in 2022 at the Free University of Berlin, in conjunction with the annual [International Symposium on Computational Geometry](/source/Symposium_on_Computational_Geometry).[1] At the same International Symposium on Computational Geometry, Alt's work with Michael Godau on using Fréchet distance to measure the similarity of shapes (announced at the 1992 symposium and published in a 1995 journal paper) was given the SoCG Test of Time Award.[5]

## Selected publications

### Edited volumes

- *Computational Discrete Mathematics: Advanced Lectures* (Springer, LNCS 2122, 2001)

- *Efficient Algorithms: Essays Dedicated to Kurt Mehlhorn on the Occasion of His 60th Birthday* (with [Susanne Albers](/source/Susanne_Albers) and Stefan Näher, Springer, LNCS 5760, 2009)

- *Algorithms Unplugged* (with B. Vöcking, M. Dietzfelbinger, R. Reischuk, C. Scheideler, H. Vollmer, and [D. Wagner](/source/Dorothea_Wagner), Springer, 2011)

### Research articles

- Alt, H.; Blum, N.; [Mehlhorn, K.](/source/Kurt_Mehlhorn); Paul, M. (1991), "Computing a maximum cardinality matching in a bipartite graph in time O ( n 1.5 m / log ⁡ n ) {\textstyle O(n^{1.5}{\sqrt {m/\log n}})} ", *[Information Processing Letters](/source/Information_Processing_Letters)*, **37** (4): 237–240, [doi](/source/Doi_(identifier)):[10.1016/0020-0190(91)90195-N](https://doi.org/10.1016%2F0020-0190%2891%2990195-N), [MR](/source/MR_(identifier)) [1095712](https://mathscinet.ams.org/mathscinet-getitem?mr=1095712)

- Alt, Helmut; Behrends, Bernd; Blömer, Johannes (1995), ["Approximate matching of polygonal shapes"](https://refubium.fu-berlin.de/handle/fub188/18675), *Annals of Mathematics and Artificial Intelligence*, **13** (3–4): 251–265, [doi](/source/Doi_(identifier)):[10.1007/BF01530830](https://doi.org/10.1007%2FBF01530830), [MR](/source/MR_(identifier)) [1335736](https://mathscinet.ams.org/mathscinet-getitem?mr=1335736), [S2CID](/source/S2CID_(identifier)) [16275664](https://api.semanticscholar.org/CorpusID:16275664)

- Alt, Helmut; Godau, Michael (1995), "Computing the Fréchet distance between two polygonal curves", *[International Journal of Computational Geometry and Applications](/source/International_Journal_of_Computational_Geometry_and_Applications)*, **5** (1–2): 75–91, [doi](/source/Doi_(identifier)):[10.1142/S0218195995000064](https://doi.org/10.1142%2FS0218195995000064), [MR](/source/MR_(identifier)) [1331177](https://mathscinet.ams.org/mathscinet-getitem?mr=1331177)

- Alt, Helmut; [Mehlhorn, Kurt](/source/Kurt_Mehlhorn); Wagener, Hubert; [Welzl, Emo](/source/Emo_Welzl) (1988), "Congruence, similarity, and symmetries of geometric objects", *[Discrete & Computational Geometry](/source/Discrete_%26_Computational_Geometry)*, **3** (3): 237–256, [doi](/source/Doi_(identifier)):[10.1007/BF02187910](https://doi.org/10.1007%2FBF02187910), [MR](/source/MR_(identifier)) [0937285](https://mathscinet.ams.org/mathscinet-getitem?mr=0937285)

- Alt, Helmut; Efrat, Alon; Rote, Günter; [Wenk, Carola](/source/Carola_Wenk) (2003), "Matching planar maps", *Journal of Algorithms*, **49** (2): 262–283, [doi](/source/Doi_(identifier)):[10.1016/S0196-6774(03)00085-3](https://doi.org/10.1016%2FS0196-6774%2803%2900085-3), [MR](/source/MR_(identifier)) [2014509](https://mathscinet.ams.org/mathscinet-getitem?mr=2014509), [S2CID](/source/S2CID_(identifier)) [3998112](https://api.semanticscholar.org/CorpusID:3998112)

## References

1. ^ [***a***](#cite_ref-raf_1-0) [***b***](#cite_ref-raf_1-1) [***c***](#cite_ref-raf_1-2) [***d***](#cite_ref-raf_1-3) ["Rote–Alt Fest"](https://www.inf.fu-berlin.de/inst/ag-ti/socg22/raf.html), *Computational Geometry Week*, Free University of Berlin, 2022, retrieved 2022-10-21

1. **[^](#cite_ref-fub_2-0)** [*Prof. a.D. Dr. Helmut Alt*](https://www.mi.fu-berlin.de/inf/groups/ag-ti/members/professoren/Alt_Helmut.html), Free University of Berlin, 18 January 2007, retrieved 2022-10-21

1. ^ [***a***](#cite_ref-mg_3-0) [***b***](#cite_ref-mg_3-1) [Helmut Alt](https://mathgenealogy.org/id.php?id=51000) at the [Mathematics Genealogy Project](/source/Mathematics_Genealogy_Project)

1. **[^](#cite_ref-ha65_4-0)** [*HA65: A symposium in honor of Helmut Alt's 65th birthday*](https://www.inf.fu-berlin.de/inst/ag-ti/ha65/), Free University of Berlin, 20 June 2015, retrieved 2022-10-21

1. **[^](#cite_ref-tot_5-0)** ["Awards"](https://www.inf.fu-berlin.de/inst/ag-ti/socg22/awards.html), *CG:WEEK 2022*, Free University of Berlin, retrieved 2022-10-21

## External links

- [Helmut Alt](https://scholar.google.com/citations?user=FYVWsAsAAAAJ) publications indexed by [Google Scholar](/source/Google_Scholar)

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