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By Katrin Tent, Martin Ziegler. Katrin Tent is Professor of Mathematics at Westfälische Wilhelms-Universität Münster, Germany. Martin Ziegler is a Professor of Mathematics at Albert-Ludwigs-Universität Freiburg, Germany.
When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.