Tamal Dey

Tamal Krishna Dey (born 1964)[1] is an Indian mathematician and computer scientist specializing in computational geometry and computational topology. He was a former professor and chair of the department of computer science and engineering at the Ohio State University.

Tamal K. Dey at the MFO, 2012

Education and career

Dey graduated from Jadavpur University in 1985, with a bachelor's degree in electronics. He earned a master's degree from the Indian Institute of Science Bangalore in 1987, and completed his Ph.D. at Purdue University in 1991.[2] His dissertation, Decompositions of Polyhedra in Three Dimensions, was supervised by Chandrajit Bajaj.[3]

After postdoctoral research with Herbert Edelsbrunner at the University of Illinois at Urbana–Champaign, Dey joined the Purdue faculty in 1992. He moved to the Indian Institute of Technology Kharagpur in 1994, and moved again to Ohio State in 1999. At Ohio State, he has also held a courtesy appointment in the department of mathematics since 2015.[2]

Contributions

Dey is known for proving the tightest-known upper bounds on the k-set problem[4] and for his work on 3D reconstruction and computational topology.

He is the author of the book Curve and Surface Reconstruction: Algorithms with Mathematical Analysis (Cambridge University Press, 2006).[5] With Siu-Wing Cheng and Jonathan Shewchuk, he is the co-author of Delaunay Mesh Generation (CRC Press, 2012).[6]

Recognition

Dey was elected as an ACM Fellow in 2018 for "contributions to computational geometry and computational topology".[7] He is also a fellow of the IEEE.[2]

gollark: Git stands for GIT Is Tremendous.
gollark: The stages of git clone are: Receive a "pack" file of all the objects in the repo database Create an index file for the received pack Check out the head revision (for a non-bare repo, obviously)"Resolving deltas" is the message shown for the second stage, indexing the pack file ("git index-pack").Pack files do not have the actual object IDs in them, only the object content. So to determine what the object IDs are, git has to do a decompress+SHA1 of each object in the pack to produce the object ID, which is then written into the index file.An object in a pack file may be stored as a delta i.e. a sequence of changes to make to some other object. In this case, git needs to retrieve the base object, apply the commands and SHA1 the result. The base object itself might have to be derived by applying a sequence of delta commands. (Even though in the case of a clone, the base object will have been encountered already, there is a limit to how many manufactured objects are cached in memory).In summary, the "resolving deltas" stage involves decompressing and checksumming the entire repo database, which not surprisingly takes quite a long time. Presumably decompressing and calculating SHA1s actually takes more time than applying the delta commands.In the case of a subsequent fetch, the received pack file may contain references (as delta object bases) to other objects that the receiving git is expected to already have. In this case, the receiving git actually rewrites the received pack file to include any such referenced objects, so that any stored pack file is self-sufficient. This might be where the message "resolving deltas" originated.
gollark: UPDATE: this is wrong.
gollark: > Git uses delta encoding to store some of the objects in packfiles. However, you don't want to have to play back every single change ever on a given file in order to get the current version, so Git also has occasional snapshots of the file contents stored as well. "Resolving deltas" is the step that deals with making sure all of that stays consistent.
gollark: A lot?

References
  1. Birth year from Library of Congress catalog entry, retrieved 2018-12-06.
  2. Curriculum vitae (PDF), retrieved 2018-12-06
  3. Tamal Dey at the Mathematics Genealogy Project
  4. Mitchell, Joseph S. B.; O'Rourke, Joseph (2001), "Computational geometry column 42", International Journal of Computational Geometry & Applications, 11 (5): 573–582, arXiv:cs/0001025, doi:10.1142/S0218195901000651, MR 1862888
  5. Sottile, Matthew J. (March 2010), "Review of Curve and Surface Reconstruction: Algorithms with Mathematical Analysis", ACM SIGACT News, 41 (1): 24, doi:10.1145/1753171.1753178
  6. Bihlo, Alexander, "Review of Delaunay Mesh Generation", Mathematical Reviews, MR 3156288
  7. 2018 ACM Fellows Honored for Pivotal Achievements that Underpin the Digital Age, Association for Computing Machinery, December 5, 2018
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