27/04/2022

'Mathematics needs its own air,' says doctoral student.

The first time Zoraida Fernandez-Rico set foot in Rio de Janeiro was in 2016, when she disembarked from a plane on her way to her master's degree at IMPA. Since then, the current doctoral student has been involved with the city and, this Friday (29), at 1 pm, she concludes another stage in her academic training. After graduating with her master's degree from the institute, she will present the thesis “Optimal estimation: sub-Gaussian properties, heavy tail and robustness”. The defense will take place in room 232 and will be broadcast online.

Guided by IMPA researcher Roberto Imbuzeiro, the thesis was partly developed remotely due to the Covid-19 pandemic. The student says that she became more introspective during the pandemic, but despite this, she did not give up. “ The video calls with my advisor always motivated me. There is a magic in discussing mathematics with Roberto, who managed to create a great working environment even in the midst of a pandemic… He is an excellent mathematician and has a big heart. When we wanted to formalize the IMPA students' seminar, for example, we did not hesitate to ask for his help,” she said.

The work addresses optimal statistical estimation for finite samples from the perspectives of robustness and heavy-tailed data. “We studied two problems: properties of the truncated mean and estimation of the covariance matrix. Our main result is that the truncated mean achieves almost Gaussian bounds for observations that are not necessarily of this type. In fact, the observations can be very badly behaved. We are also interested in designing optimal estimators for other objects such as the covariance matrix,” he explains.

Life and academic career

Born in Cochabamba, a city in central Bolivia, Zoraida grew up in a house built almost 200 years ago, surrounded by culture and gatherings set to the sounds of Latin American folklore. Although Cochabamba means "plain between the waters" in Quechua — one of Bolivia's indigenous languages—the abundance of this natural resource did not guarantee a potable water and sewage system for the region's inhabitants. Known as the "Water War," the popular mobilization of Bolivians against the privatization of the municipal water management system in 2000 left a mark on the doctoral candidate's history.

“It was the first time, for example, that I experienced a state of siege. Since then, I have witnessed people trying to leave the city, seeking a better future. The songs, the films, the conversations in restaurants, everything was about the illusion of leaving. Even my school play dealt with this. I played the role of a migrant,” he recalls.

The daughter of a geneticist, science was as present as art in the doctoral candidate's childhood, who had a wide variety of interests: literature, physics, mathematics, among other topics. Her professional choice in the field of exact sciences was by chance. “I came to mathematics by mistake at the right time. Gabriel Garcia Márquez knew how to err with precision, I didn't. I was lucky and had the pleasure of being able to do what I wanted. And I know that many girls in my country don't have that choice. They also don't have that opportunity to err,” she commented.

For her undergraduate studies, she chose to study mathematics at the Universidad Mayor de San Andrés in La Paz, Bolivia. Accustomed to living in the city, which is more than 3,600 meters above sea level, Zoraida traded La Paz for Rio de Janeiro to begin her master's degree at IMPA. Upon landing in the capital of Rio de Janeiro, she immediately felt the abrupt change in the air, marked by humidity. "When I got off the plane, I felt like I was entering a sauna. And I never left," she said.

The doctoral candidate says she felt satisfied with her experience at the institute from the beginning. “The most important thing that has happened to me in life has always been the people. My undergraduate and graduate studies allowed me to share journeys, narratives, and camaraderie with wonderful people who now live in my heart.”

At an academic level, the doctoral candidate described her journey as "formative, beautiful, and frustrating." "Sometimes, mathematics became too 'dry' for me, and I felt lost. Finding your way can take time, returning to the starting point may not be possible, moving forward can take you further away. Sometimes we have to stop to breathe. I think mathematics needs its own air," she said.

Women in mathematics

Zoraida's dedication to her studies doesn't prevent her from making time for other passions, such as reading, the sea, and cinema. In recent years, much of her time has been dedicated to discussions about gender representation in mathematics. The Bolivian mathematician participated in organizing events such as the first and second IMPA Women Mathematicians Meetings.

“I think that becoming a woman in mathematics has a little bit to do with recognizing oneself through other women mathematicians. Participating in these groups gives me a sense of belonging. I had role models like Carolina and Luna, which was very important because past generations didn't have them,” she said.

And, if it depends on mathematics, there is still much change to come in this scenario. "I plan to continue participating in groups of women mathematicians in the future. I would very much like to form the first society of women and diverse mathematicians in Bolivia," she added.