Geography, Ties, and Knowledge Flows: Evidence from Citations in Mathematics

We thank Mitch Keller at the Mathematics Genealogy Project and Nicolas Roy from zentralblatt-math.org for data. Yao Amber Li acknowledges financial support from the Research Grants Council of Hong Kong, China (General Research Funds Project 643311), and Asier Minondo from the Spanish Ministry of Economy and Competitiveness (MINECO ECO2016-79650-P cofinanced with FEDER), the Spanish Ministry of Science, Innovation and Universities (RTI2018-100899-B-100, confinanced with FEDER), and the Basque Government Department of Education, Language Policy and Culture (IT885-16). Seminar participants at Dartmouth, LSE, Oxford, UBC, Glasgow, Birmingham, and Nottingham made helpful suggestions. We also thank Andrew Bernard, Teresa Fort, Joshua Gottlieb, Bob Staiger, Bronwyn Hall, Wolfgang Keller, Anthony J. Venables, Quoc-Anh Do, Edwin Lai, Jim MacGee, Andrés Rodríguez-Clare, Daniel Sturm, Dave Donaldson, Ben Faber, and Pablo Fajgelbaum for valuable discussions. We thank Michal Fabinger for alerting us to the importance of arXiv.org for knowledge dissemination over the Internet. We are particularly grateful to Andrei Levchenko for raising issues that led to the results in section IVB. Ho Yin Tsoi, Bo Jiang, Yiye Cui, and Song Liu provided excellent research assistance during this project. Finally, we thank three anonymous referees and Amit Khandelwal for very helpful suggestions.

A supplemental appendix is available online at http://www.mitpressjournals.org/doi/suppl/10.1162/rest_a_00771.