STEFFEN LEMPP

Office Address

Email/Office

Logic seminars around the Midwest

• UW Logic Seminar
• UW Graduate Logic Seminar
• UW CS Theory Seminar
• Midwest Computability Seminar (a joint seminar of the University of Wisconsin-Madison, the University of Chicago, the University of Illinois-Chicago and the University of Notre Dame, held once or twice a semester on the University of Chicago campus)
• Midwest Model Theory Seminar (a joint seminar of the University of Wisconsin-Madison, the University of Illinois-Chicago and the University of Notre Dame, held once a semester on the University of Illinois at Chicago campus)
• University of Chicago Logic Seminar
• Louise Hay Logic Seminar, University of Illinois-Chicago
• University of Illinois-Chicago Logic Seminar
• Notre Dame Logic Seminar
• Indiana University Logic Seminar

Conferences I plan to attend

• May 13-16, 2025: 2025 ASL North American Annual Meeting, New Mexico State University, Las Cruces
• July 7-11, 2025: 2025 European Logic Colloquium, Technical University of Vienna, Austria

My research interests

Some particular problems I have been working on, or would be interested in working on again, include

• algebraic structures of, and decidability of fragments of theories of, degree structures (esp. the c.e. Turing degrees, the d.c.e. and n-c.e. Turing degrees, the global enumeration degrees, the Σ⁰₂-enumeration degrees, and the Weihrauch degrees),
• computability-theoretic aspects of equivalence relations on the integers, Cantor space and Baire space,
• computable numberings of families of sets, esp. finite families of c.e. sets,
• c.e. and other equivalence relations and their structure,
• computable algebraic structures, such as linear orders, Boolean algebras, and groups,
• characterization of computable algebraic structures by classical invariants (e.g., Ketonen invariants and Ulm invariants),
• degrees of models of א₁-categorical theories, and more generally of trivial theories of finite Morley rank,
• proof-theoretical strength and first-order consequences of combinatorial principles related to Ramsey's Theorem for pairs, and
• equivalence of Martin-Löf randomness with other notions of randomness (in particular Kolmogorov-Loveland randomness).

My curriculum vitae, bibliography, and mathematical genealogy

• My CV
• My math genealogy (collated by my former student Chris Alfeld)

My publications on line

• Titles, abstracts, and pdf files

Lobachevskii Journal of Mathematics

Submissions in mathematical logic, especially in computability theory and its applications, can be sent directly to me by email at @math.wisc.edu">lemppmath.wisc.edu. Before submission, be sure to consult the instructions on how to prepare your manuscript.

Professional Organizations

• Association for Symbolic Logic (ASL)
• American Mathematical Society (AMS)
• Mathematical Association of America (MAA)
• Association for Mathematical Research (AMR)
• Deutsche Mathematiker-Vereinigung (DMV)
• Deutsche Vereinigung für Mathematische Logik und für Grundlagen der Exakten Wissenschaften (DVMLG)
• Computability in Europe (CiE)
• Association for Women in Mathematics (AWM)
• European Mathematical Society (EMS)
• Canadian Mathematical Society (CMS)
• American Philosophical Association (APA)
• Association for Computing Machinery (ACM) (with Special Interest Group in Logic and Computations (SIGLOG))

Research databases of interest to logicians

• AMS 2020 Mathematics Subject Classifications
• arXiv.org in logic (open-access database of papers in math and science, maintained by Cornell University)
• Bibliography on Boolean algebras (maintained by Don Monk, University of Colorado)
• Computability theory (list server maintained by Bjørn Kjos-Hanssen, University of Hawai'i-Mānoa)
• Computer Science Bibliography (maintained by the University of Trier, Germany)
• European Mathematical Information Service (EMIS) (a central portal for electronic math resources in Europe)
• Forking and Dividing: Map of the Universe (maintained by Gabe Conant)
• Göttinger DigitalisierungsZentrum (GDZ) (an open-access database of many resources in mathematics, mainly from German-speaking and Eastern European countries, maintained by the University of Göttingen, e.g., Algebra and Logic (in Russian))
• JSTOR (Journal Storage, maintained by the Carnegie Mellon Foundation, requires subscription by your institution, or ASL membership)
• Lattice Drawing (maintained by Ralph Freese, University of Hawai'i-Mānoa)
• Logic Mailing List (maintained by the Bonn Mathematical Logic Group)
• Math-Net.Ru: All-Russian Mathematical Portal (maintained by Steklov Mathematical Institute of the Russian Academy of Sciences)
• Math journal price surveys (maintained by Ulf Rehmann, Bielefeld, Germany)
• Mathematics Genealogy Project (maintained by North Dakota State University)
• Mathoverflow in logic (a place for mathematicians to ask and answer questions)
• Open Logic Project (an open source logic text in adjustable modules, with some prebuilt versions, instigated by Richard Zach)
• Project Euclid (a non-profit journal database maintained by Cornell University and primarily funded by the Mellon Foundation)
• Proof Theory Blog
• Shelah Archive (maintained by Technical University of Vienna, Austria)
• zbMATH (Zentralblatt search for math papers; now free access)
• Zoo Viewer (non-implications in various arease of computability theory, maintained by Damir Dzhafarov and Ludovic Levy Patey)

ASL Committee on Translations

Please send your suggestions to one of the committee members: Zhaokuan Hao (Fudan University, Shanghai, China), Iskander Kalimullin (Kazan Federal University, Russia), Hiroakira Ono (Japan Advanced Institute of Science and Technology (JAIST), Ishikawa, Japan), Todor Tsankov (University of Lyon 1, France), Andrés Villaveces (Universidad Nacional de Colombia, Bogotá, Colombia), or me (@math.wisc.edu">lemppmath.wisc.edu).

Information for Russian-speaking Logicians

I also administer the program of the Association for Symbolic Logic (ASL) offering

For more information about this program, click here for information in English or in Russian.

Home pages of some other logicians

• Uri Andrews, University of Wisconsin-Madison
• Andy Arana, University of Lorraine, Nancy and Paris. France
• Marat Arslanov, Kazan Federal University, Russia
• Matthias Aschenbrenner, University of Vienna, Austria
• Jeremy Avigad, Carnegie Mellon University
• Serikzhan Badaev, Kazakh National University, Almaty
• John Baldwin, University of Illinois-Chicago
• George Barmpalias, Chinese Academy of Sciences, Beijing, China
• Kolya Bazhenov, Sobolev Institute of Mathematics, Novosibirsk, Russia
• Verónica Becher, University of Buenos Aires, Argentina
• Itaï BEN YAACOV, University of Lyon, France
• Michael Benedikt, Oxford University, England
• Laurent Bienvenu, University of Bordeaux, France
• Steve Binns, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
• Vasco Brattka, University of the Army, Munich, Germany
• Katie Brodhead, Florida State University, Panama City
• Jin-Yi Cai, University of Wisconsin-Madison
• Wesley Calvert, Southern Illinois University, Carbondale
• Doug Cenzer, University of Florida, Gainesville
• Artem Chernikov, University of Los Angeles-California
• Peter Cholak, University of Notre Dame
• Chi Tat Chong, National University of Singapore
• Vittorio Cipriani, Technical University of Vienna, Austria
• Chris Conidis, City University of New York-College of Staten Island
• Barbara Csima, University of Waterloo, Ontario, Canada
• Arman Darbinyan, University of Southampton, England
• Natasha Dobrinen, University of Notre Dame, Indiana
• Rod Downey, Victoria University of Wellington, New Zealand
• Damir Dzhafarov, University of Connecticut-Storrs
• Marat Faizrahmanov, Kazan Federal University, Russia
• Marta FIORI CARONES, Sobolev Institute of Mathematics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk
• Katia Fokina, Vienna University of Technology, Austria
• Johanna Franklin, Hofstra University, Hempstead, New York
• Jim Freitag, University of Illinois-Chicago
• Harvey Friedman, Ohio State University, Columbus
• Sy David Friedman, Kurt Gödel Research Center for Mathematical Logic (KGRC), Vienna, Austria
• Andrey Frolov, Kazan Federal University, Russia
• Hristo Ganchev, Sofia University, Bulgaria
• Su GAO, Nankai University, Tianjin, China
• Peter Gerdes, Indiana University, Bloomington
• Jun Le GOH, National University of Singapore
• Isaac Goldbring, University of California-Irvine
• Sergey Goncharov, Siberian Branch of the Russian Academy of Sciences and Novosibirsk State University, Russia
• Noam Greenberg, Victoria University of Wellington, New Zealand
• Valentina Harizanov, George Washington University, Washington, D.C.
• Matthew Harrison-Trainor, University of Illinois-Chicago
• Denis Hirschfeldt, University of Chicago, Illinois
• Jeff Hirst, Appalachian State University, Boone, North Carolina
• Meng-Che ("Turbo") Ho, California State University, Northridge
• Steve Jackson, University of North Texas, Denton
• Carl Jockusch, University of Illinois at Urbana-Champaign
• Asher Kach, Google-Chicago
• Iskander Kalimullin, Kazan Federal University, Russia
• Jerry Keisler, University of Wisconsin-Madison
• Bakhadyr Khoussainov, University of Auckland, New Zealand and University of Electronic Science and Technology of China, Chengdu, China
• Takayuki Kihara, Nagoya University, Japan
• Byunghan Kim, Yonsei University, Seoul, South Korea
• Bjørn Kjos-Hanssen, University of Hawai'i-Mānoa
• Ulrich Kohlenbach, University of Darmstadt, Germany
• Leszek Kołodziejczyk, University of Warsaw, Poland
• Chris Laskowski, University of Maryland-College Park
• Ludovic LEVY PATEY, University of Paris Diderot, France
• Andy Lewis-Pye, London School of Economics, England
• Jack Lutz, Iowa State University, Ames
• Maryanthe Malliaris, University of Chicago, Illinois
• Alberto Marcone, University of Udine, Italy
• Dave Marker, University of Illinois-Chicago
• Andrew Marks, University of California-Berkeley
• Tim McNicholl, Iowa State University, Ames
• Sasha Mel'nikov, Victoria University of Wellington, New Zealand
• Joe Mileti, Grinnell College, Grinnell, Iowa
• Arnie Miller, University of Wisconsin-Madison
• Joe Miller, University of Wisconsin-Madison
• Russell Miller, Queens College, New York City
• Benoît Monin, University of Paris-Est Créteil, France
• Antonio Montalbán, University of California-Berkeley
• Andrey Morozov, Novosibirsk State University and Russian Academy of Sciences, Russia
• Carl Mummert, Marshall University, Huntington, West Virginia
• Manat Mustafa, Nazarbayev University, Astana, Kazakhstan
• Ronnie Nagloo, University of Illinois-Chicago
• Satya Nandakumar, Indian Institute of Technology, Kanpur
• Keng Meng (Selwyn) NG, Nanyang Technological University, Singapore
• André Nies, University of Auckland, New Zealand
• Arno Pauly, Swansea University, Wales
• Misha Peretyat'kin, Institute of Mathematics, Almaty, Kazakhstan
• Anand Pillay, University of Notre Dame, Indiana
• Dilip Raghavan, National University of Singapore
• Jan Reimann, Pennsylvania State University, University Park
• Christian Rosendal, University of Maryland, College Park
• Dino Rossegger, Technical University of Vienna, Austria
• Wim Ruitenburg, Marquette University, Milwaukee, Wisconsin
• Luca SAN MAURO, Technical University of Vienna, Austria, and University of Bari, Italy
• Andre Scedrov, University of Pennsylvania, Philadephia
• Noah Schweber, Proof School, San Franscisco, California
• Paul Shafer, University of Leeds, England
• Sasha Shlapentokh, East Carolina University, Greenville, North Carolina
• Richard Shore, Cornell University, Ithaca, New York
• Steve Simpson, Pennsylvania State University, State College and Vanderbilt University, Nashville, Tennessee
• Ted Slaman, University of California-Berkeley
• Reed Solomon, University of Connecticut-Storrs
• Andrea Sorbi, University of Siena, Italy
• Mariya Soskova, University of Wisconsin-Madison
• Patrick Speissegger, McMaster University, Hamilton, Ontario, Canada
• Frank Stephan, National University of Singapore
• Bas Terwijn, Radboud University Nijmegen, The Netherlands
• Henry Towsner, University of Pennsylvania, Philadelphia
• Todor Tsankov, University of Lyon 1, France
• Anush Tserunyan, McGill University, Montreal, Canada
• Dan Turetsky, Victoria University of Wellington, New Zealand
• Manlio Valenti, University of Wisconsin-Madison
• Dieter van Melkebeek, University of Wisconsin-Madison
• Peter Vranas, University of Wisconsin-Madison
• Wei WANG, Sun Yat-sen University, Guangzhou, China
• Andreas Weiermann, Ghent University, Belgium
• Linda Westrick, Pennsylvania State University
• Alex Wilkie, University of Oxford, England
• Guohua Wu, Nanyang Technological University, Singapore
• Mars Yamaleev, Kazan Federal University
• Yue YANG, National University of Singapore
• Keita Yokoyama, Tohoku University, Sendai, Japan
• Liang YU, Nanjing University, China
• Ning ZHONG, University of Cincinnati, Ohio
• Boris Zil'ber, University of Oxford, England
• Andy Zucker, University of Waterloo, Ontario, Canada