Articles in this volume are based on presentations given at the IV Meeting of Mexican Mathematicians Abroad (IV Reunion de Matematicos Mexicanos en el Mundo), held from June 10-15, 2018, at Casa Matematica Oaxaca (CMO), Mexico. This meeting was the fourth in a series of ongoing biannual meetings bringing together Mexican mathematicians working abroad with their peers in Mexico. This book features surveys and research articles from five broad research areas: algebra, analysis, combinatorics, geometry, and topology. Their topics range from general relativity and mathematical physics to interactions between logic and ergodic theory. Several articles provide a panoramic view of the fields and problems on which the authors are currently working on, showcasing diverse research lines complementary to those currently pursued in Mexico. The research-oriented manuscripts provide either alternative approaches to well-known problems or new advances in active research fields. This book is published in cooperation with Sociedad Matematica Mexicana.