premise: The 2010–11 Tour de Ski was the 5th edition of the Tour de Ski and took place from 31 December 2010 to 9 January 2011. The race started in Oberhof, Germany, and ended in Val di Fiemme, Italy. The defending champions were Lukáš Bauer of the Czech Republic for the men and Poland's Justyna Kowalczyk for the women. Kowalczyk defende her title, and Swiss Dario Cologna won the Men's class.
hypothesis: The men's and women's races were held simultaneously.
reason: The men's and women's races may or may not have been simultaneously held.