Henri Cartan

Henri Cartan was a brilliant mathematician from France who changed how we see shapes and numbers.

He was born on July 8, 1904. He loved math even when he was a very young child. He did not just follow his family into math; he chose it himself. He moved to Paris in 1909 when his father took a job at the Sorbonne. Later, he studied at the Lycée Hoche in Versailles. He eventually went to the École Normale Supérieure to study deeply. He earned his doctorate in 1928 under a teacher named Paul Montel.

Cartan worked on many hard puzzles in math. He looked at how shapes could be stretched or moved. This is often called algebraic topology. He also studied how different math ideas fit together. He worked on things called complex variables and analytic geometry. He solved difficult problems like the Cousin problems. To do this, he used special tools called sheaf cohomology. He even proved two very important results called Cartan's theorems A and B. Later, he worked with Jean-Pierre Serre on a method called "killing homotopy groups."

His life was full of teaching and helping others learn. He taught at many places like the University of Lille and the University of Strasbourg. During World War II, he had to move to Clermont Ferrand. After the war, he returned to Paris to teach at the Université de Paris. He was also a founding member of the Bourbaki group in 1934. This was a group of math experts who worked together. He ran a seminar in Paris that helped many young mathematicians grow. One of his students was Joséphine Guidy Wandja, the first African woman to get a math PhD.

Cartan was a very famous leader in the math world. In 1950, he was the president of the Société mathématique de France. He also led the International Mathematics Union from 1967 to 1970. He won many big prizes for his hard work. He received the Émile Picard Medal in 1959 and the CNRS Gold Medal in 1976. In 1980, he won the prestigious Wolf Prize. He was a member of the French Academy of Sciences starting in 1974. Many other countries, like the United States and Japan, invited him to join their science groups too.

Beyond math, Cartan cared deeply about people and fairness. He used his voice to help mathematicians who were in trouble. He helped free people like Leonid Plyushch and Jose Luis Massera from prison. He wanted math experts to share ideas freely across the world. He believed in a united Europe and led a group for European Federalism. Because of his kindness, he won the Heinz R. Pagels Human Rights of Scientists Award in 1989. He lived a very long and meaningful life. He died on August 13, 2008, at the age of 104.