Picture of Steffen Lempp

Permanent Address

Department of Mathematics
University of Wisconsin
480 Lincoln Drive
Madison, WI 53706-1325


Skype: steffen.lempp

Permanent Phone/Fax

Office: +1-608-263-1975 (vacated until August 2017)
Department: +1-608-263-3054
Fax: +1-608-263-8891

(On sabbatical until August 2017! It is best to try to reach me by email.)

Temporary Address/Phone/Fax (until August 2017)

Department of Mathematics
National University of Singapore
Block S17
10 Lower Kent Ridge Road

Singapore 119076

Office: S17-05-15
Office phone: +65-65162753
Department phone: +65-65162738 or +65-65162762 or +65-65162737
Department fax: +65-67795452

Keep in mind that the current time and date in Singapore is:

Seminars in Singapore

Associate Chair Business

I was my department's associate chair until summer 2016. My successor is Tonghai Yang.

Logic seminars around the Midwest

Conferences I plan to attend (and other times I plan to be out of town)

Other conferences of interest to logicians

Web pages from past conferences I have co-organized

Travel Information on Madison and the University of Wisconsin

Madison Weather Picture of Van Vleck Hall

Travel information for foreign visitors to the UW math department

IMPORTANT NOTE FOR VISA WAIVER TRAVELERS: You will now need to pre-register at least three days before arrival in the United States at the ESTA web site. ESTA now charges US$14 for this! Be sure to bring along your ESTA receipt as well as a copy of the green form you fill out during your travel to the U.S. if we will pay you for any expenses, we cannot pay you without this receipt and this green form!

NEW: Starting in September 2016, Canada now also has a similar travel authorization system to ESTA called eTA, which is required even if you just have a flight layover in Canada. eTA is valid for five years (or until your passport expires), usually takes only minutes to complete, and costs CAN$ 7.

Since September 11, 2001, visa regulations for foreign visitors have become much stricter. In particular, the "wrong kind" of visa can result in

In particular, a tourist visa B-2 (or tourist visa waiver WT) allows us to pay you for at most nine days of travel expenses; so you should always try to get a business visa B-1 (or business visa waiver WB) whenever you come for shorter visits over nine days. If you are eligible for a visa waiver (check here for the list of eligible countries), then you should make sure at the border that you show the immigration official an official letter of invitation from us and that the immigration official circles "WB" on your entry stamp in your passport. Do not leave from this official until your passport stamp is correct, since this cannot be changed later on!

Also note that if your travel to and from the U.S. is supported by a federal grant (such as an NSF grant), then you need to abide by the Fly America Act (see Article 14c+d in this document), which generally requires the use of U.S. carriers to the closest foreign airport served by a U.S. airline. However, several Open Skies Agreements have recently been signed (currently with the European Union, Switzerland, Australia and Japan), which allow use of these countries' airlines as well. Note, however, that what matters for the Fly America Act is the airline listed on your ticket and not the airline actually flying the plane, which can become tricky with all the code sharing! Here are some useful links:

State Department web sites on U.S. visas

Related information for visitors

My research interests

My primary research interest is computability in its various aspects, both in classical computability theory, in particular degree structures, and in applications of computability to model theory, algebra, proof theory, and computer science.

Some particular problems I am currently working on include

My curriculum vitae, bibliography, and mathematical genealogy

My publications on line

Bulletin of Symbolic Logic

I am one of the reviews editors for the Bulletin of Symbolic Logic. The reviews published quarterly in the Bulletin of Symbolic Logic (under the auspices of the Association for Symbolic Logic) serve to inform the logic research community of selected books and articles, as well as sets of articles on a common theme.

If you have suggestions for reviews or would like to submit a review, please contact me by email at"> Suggestions for reviewers can be found here. Reviewers are asked (but not required) to use latex with the ASL review style file (with instructions).

Lobachevskii Journal of Mathematics

In March 2015, I became one of the editors for this journal established by the Russian Academy of Sciences and Kazan State University and distributed by Springer-Verlag.

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

Professional Organizations

Research databases of interest to logicians

Job openings I happen to hear of

Information on special Ph. D. and Master's Programs in Logic

Summer Schools in Logic for Undergraduate and Graduate Students

Information for Russian-speaking Logicians

The ASL Committee on Translations offers a
Russian translation of Bruno Poizat's
"Cours de théorie des modèles" ("A Course in Model Theory")
for free download.

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

free subscriptions to
the Journal of Symbolic Logic and the Bulletin of Symbolic Logic
to university libraries in the non-EU countries of the former Soviet Union.

For more information about this program, click here for information in English or in Russian (KOI-8 encoding or Windows-1251 encoding).

Home pages of some other logicians

Prepared by Steffen Lempp (">