Ethnomathematics: Computations among Maya calendars

Monday, November at 4pm in Olin 201. Ximena Catepillán, PhD, professor emerita of Millersville University will talk about computations among Maya calendars. Mesoamerican calendars were many and complex. A good number of studies have been done to decipher them. By the arrival of Hernan Cortes in 1519 in what current day Mexico is, there were 21 calendars in use while 4 of them were extinct. Using astronomical observations, the Maya developed an elaborate system of calendars, among them the Tzolkin Calendar, the Haab Calendar, the Round Calendar, and the Long Count. Which operations did the Maya use to perform their calendrical computations? While they used a vigesimal system to write the numbers, this system was never used in connection with days. No inscriptions use vigesimal numbers but rather quasi-vigesimal numbers. In spoken numbers, a mix of decimal and vigesimal notation appears.  They also needed to divide to do some of the calendar conversions. Ximena will illustrate calendrical computation within and among calendars and conversion examples in which division is needed.

BIO: Professor emerita at Millersville University of Pennsylvania and Chilean mathematician, Ximena Catepillán has indigenous roots in South America and is passionate about the mathematics of the Pre-Columbian Americas. She earned her PhD in Mathematics from The University of Iowa and a Master’s Degree in Sciences at the same university. She taught mathematics at Universidad de Magallanes in the Chilean Patagonia before coming to the USA. After obtaining her PhD, Ximena taught mathematics at Millersville University until her retirement. In 2006, began traveling to Maya sites with archaeologists from the Maya Exploration Center. Soon after, she began teaching abroad, an ethnomathematics course she had developed at Millersville University while visiting Maya sites in Mexico, Guatemala, and Belize.

In 2016 she co-authored the textbook Mathematics in a Sample of Cultures. In addition, she created the first-year seminar: Culture, Science, and Mathematics in the pre-Columbian Cultures, and co-created a graduate course in Ethnomathematics for students at Millersville University. In 2021 she developed and has been teaching the seminar Etnomatemáticas for graduate students at Universidad de Santiago de Chile.

Ximena is currently an Associate Editor of the Convergence Journal of the MAA, she is the Chair of the History of Mathematics Interest Group of the MAA, HOM-SIGMAA, and she also chairs the Committee on the T. Christine Stevens Award for Leadership Development in Mathematics for the MAA, and is a member of the MAA Congress as the Representative-at-Large for the Interests of Members Residing outside the United States.